GIFT   OF 

MICHAEL  REESE 


LECTURES  ON  EXPLOSIVES 


A    COURSE    OF  LECTURES 


PREPARED    ESPECIALLY    AS 


A   MANUAL  AND   GUIDE 


IN    THE    LABORATORY    OF    THE 


U.  S.  ARTILLERY  SCHOOL 


BY 


WILLOUGHBY    WALKE, 

First  Lie^^tenant,  Fifth.  United  States  Artillery, 

INSTRUCTOR. 


SECOND   EDITION,   REVISED   AND  ENLARGED. 
FIRST    THOUSAND. 


NEW   YORK: 

JOHN    WILEY   &    SONS. 

LONDON:    CHAPMAN  &  HALL,  LIMITED. 

1897. 


Copyright,  i8q7, 

BY 

WILLOUGHBY  WALKE. 


ROBERT    DRUMMOND,    ELECTROTYPER    AND    PRINTER,    NEW    YORK. 


PREFACE  TO  THE  FIRST  EDITION. 


THE  following  course  of  lectures  is  intended  to  serve  as  a 
manual  and  guide  in  the  practical  laboratory-work  in  the 
course  of  explosives  at  the  U.  S.  Artillery  School. 

The  aim  has  been  to  present  the  subject  systematically 
and  logically,  due  consideration  being  given  to  the  sequence 
in  which  the  various  classes  of  explosives  are  arranged,  so  that 
a  certain  degree  of  familiarity  may  be  acquired  in  manipulat- 
ing the  less  sensitive  and  dangerous  mixtures  before  under- 
taking experiments  with  the  high  explosives. 

Particular  attention  has  been  given  to  the  service  tests  of 
the  various  explosives,  in  the  description  of  which  all 
technical  terms  have  been  avoided  as  far  as  possible. 

While  the  bulk  of  the  matter  here  presented  is  the  result 
of  compilation,  it  is  believed  that  a  portion  at  least  appears 
in  print  for  the  first  time. 

In  submitting  these  pages  I  wish  to  acknowledge  my 
indebtedness  for  assistance  and  encouragement  to  Professor 
Munroe,  and  Lieutenant-Colonel  R.  T.  Frank,  2d  Artillery, 
Commandant  of  the  Artillery  School. 

With  the  permission  of  Professor  C.  E.  Munroe,  Chemist 
to  the  U.  S.  Navy  Torpedo  Corps,  I  have  borrowed  largely 
from  his  course  of  "  Lectures  on  Chemistry  and  Explosives," 
delivered  at  the  Torpedo  Station,  the  arrangement  of  the 
subject-matter  being  slightly  changed  to  meet  the  require- 
ments of  the  Artillery  School. 

WlLLOUGHBY  WALKE, 

ist  Lieut.,  5th  Artillery. 
U.  S.  ARTILLERY  SCHOOL, 
FORT  MONROE,  VA.,  November,  1891. 

iii 


PREFACE  TO  THE  SECOND  EDITION. 


IN  preparing  the  present  edition  of  "  Lectures  on  Ex- 
plosives "  the  same  general  outline  of  the  previous  edition 
has  been  followed. 

The  subject-matter  has  been  enlarged,  and  it  is  believed 
that  the  value  and  usefulness  of  the  work  have  been  consider- 
ably increased  not  only  as  a  text-book  but  for  purposes  of 
reference. 

In  addition  to  those  friends  who  aided  me  in  the  prepara- 
tion of  the  earlier  edition  I  wish  to  acknowledge  my  indebt- 
edness particularly  to  M.  Berthelot,  Membre  de  1'Institut, 
President  de  la  Commission  des  Substances,  Explosives,  etc., 
with  whose  permission  I  have  borrowed  Chapter  II.  from 
his  work  "  Sur  la  Force  des  Matieres  Explosives  d'apres  la 
Thermochimie  " ;  and  John  W.  Mallet,  Professor  of  Gen- 
eral and  Industrial  Chemistry  in  the  University  of  Virginia. 

WlLLOUGHBY  WALKE, 
i st  Lieut.,  $th  Artillery. 

U.  S.  ARTILLERY  SCHOOL, 
FORT  MONROE,  VA.,  May,  1897. 


CONTENTS. 


LECTURE   I. 


GENERAL  CONSIDER  A  TIONS  AFFECTING  EXPLOSIONS  AND  EXPLOSIVES. 

PAGS 

Explosive  Reactions I 

The  Chemical  Composition  of  Explosives 2 

The  Origin  of  Explosive  Reactions 2 

The  Propagation  of  Explosive  Reactions 3 

Influence  of  Physical  or  Mechanical  Condition  of  the  Explosive 4 

Influence  of  External  Conditions 5 

Influence  of  Method  of  Initial  Inflammation , 6 

Combustion,  Explosion,  Detonation 7 

Bodies  susceptible  of  Detonation 9 

Products  of  Explosive  Reactions II 

The  Volume  of  Gas  evolved 12 

Temperature  of  Explosion 14 

Effect  of  Dissociation 16 

Potential  Energy  of  Explosives 17 


LECTURE   II. 

PRINCIPLES  OF    THERMOCHEMISTRY  AS  APPLIED  TO  EXPLOSIVES,  AND 
THE  CLASSIFICA  TION  AND  COMPOSITION  OF  EXPLOSIVES. 

Molecular  Work 18 

The  Calorific  Equivalence  of  Chemical  Transformations 19 

Maximum  Work 20 

Classification  and  Constitution  of  Explosives 21 

General  List  of  Explosives 22 

Explosive  Mixtures  and  Explosive  Compounds , 24 

Explosive  Mixtures 24 

Explosive  Compounds 25 

Composition  of  Explosives 26 

vii 


Vlll  CONTENTS. 


LECTURE  III. 

INGREDIENTS  ENTERING  INTO  THE  COMPOSITION  OF  EXPLOSIVES,  AND 
SUBSTANCES  USED  IN  THEIR  PREPARA  TION. 

PAGE 

Potassium  Nitrate 29 

Sodium  Nitrate 31 

Ammonium  Nitrate 32 

Barium,  Lead,  and  Strontium   Nitrates 32 

General  Qualitative  Tests  applicable  to  All  Nitrates 33 

Quantitative  Tests  for  Nitre 36 

Potassium  Chlorate , 38 

Qualitative  Tests  for  Chlorates 39 

Nitric  Acid 40 

Tests  for  Nitric  Acid 41 

Charcoal - 42 

Tests  for  Charcoal 44 

Sulphur 45 

Tests  for  Sulphur 46 

Sulphuric  Acid , 46 

Tests  for  Sulphuric  Acid 48 

Hydrocarbons * 49 

Benzene 50 

Tests  for  Benzene 50 

Toluene 51 

Naphthalene 51 

Carbohydrates 52 

Cellulose 52 

Alcohols 53 

Glycerine 55 

Tests  for  Glycerine 55 

Ethers 57 

Acetone 59 

Camphor,  Vaseline,  Paraffin,  Wax,  etc 61 

Kieselguhr,  Randanite,  etc 63 


LECTURE   IV. 

CLASSIFICA  TION  OF  EXPLOSIVE  MIXTURES.    EXPLOSIVE  MIXTURES  OF 
THE  NITRA  TE  CLASS. 

Explosive  Mixtures  of  the  Nitrate  Class 64 

Gunpowder 65 

Refining  Saltpetre 66 

Sulphur 69 

Charcoal 71 

Charcoal-grinding  Mill 73 


CONTENTS.  IX 


Saltpetre-  and  Sulphur-grinding  Apparatus 75 

Manufacture  of  Gunpowder 76 


LECTURE  V. 

GUNPO  VVDER-(  Continued). 

Special  Powders , 84 

Hexagonal  Powder 86 

Manufacture  of  Hexagonal  Powder 86 

Perforated  Prismatic  Powder 87 

Manufacture  of  Perforated  Prismatic  Powder 88 

Pellet  Powder   go 

Manufacture  of  Pellet  Powder gi 

Cubical  Powder g3 

Manufacture  of  Cubical  Powder g3 

Modifications  in  the  Manufacture  of  Gunpowder , g3 

Process  followed  at  the  Augusta,  Ga.,  Mills ! g4 

Wiener  Process g5 

Nordenfelt  and  Meurling  Process g5 

Modifications  in  the  Composition  of  Gunpowder , 95 

Brown  Prismatic  or  Cocoa  Powder g6 

Properties  peculiar  to  Cocoa  Powder 97 

Du  Pont  Brown  Powder 98 

Amide  Powder 100 

Quick  Powder , 102 

Noble's  Powder 103 

Saxif  ragine 103 

Blasting-powders 104 

LECTURE   VI. 

G  UNFO  WDER—(  Contin  ued  ). 

Properties  of  Gunpowder 106 

Tests  for  Gunpowder 109 

Analysis  of  Gunpowder , 109 

Determination  of  the  Hygroscopic  Quality  of  the  Powder 115 

Test  for  Proper  Incorporation 116 

•Granulation  and  Hardness 118 

Preservation,  Storage,  and  Transportation  of  Gunpowder «  119 

LECTURE   VII. 

DENSIMETRY. 

Densimetry 122 

The  Mallet  Densimeter 123 


X  CONTENTS. 

PAGE 

Precautions  to  be  observed  in  using  the  Mallet  Densimeter 125 

The  Process  of  determining  the  Density  of  a  Sample  of  Powder 127 

The  Du  Pont  Densimeter 1 29 

Precautions  to  be  observed  in  using  the  Du  Pont  Densimeter 132 

To  determine  the  Density  of  Powder  with  the  Du  Pont  Densimeter 133 

Gravimetric  Density  of  Gunpowder 136 

The  Du  Pont  Gravimetric  Balance 138 

Precautions  to  be  observed  in  the  Care  and  Use  of  the  Du  Pont  Gravimetric 

Balance 139 

The  Determination  of  the  Gravimetric  Density  of  Gunpowder  with  the  Du 

Pont  Gravimetric  Balance 140 

The  Gravimeter  140 

How  to  use  the  Gravimeter 141 


LECTURE   VIII. 
THE  CHEMICAL  THEORY  OF  THE  COMBUSTION  OF  GUNPOWDER. 

Noble  and  Abel's  Calculations 143 

Berthelot's  Theory 144 

Debus'  Theory 146 

Recapitulation 151 

LECTURE    IX. 
EXPLOSIVE  MIXTURES  OF  THE  CHLORA  TE  CLASS. 

Chlorate  Mixtures 154 

Asphaline  . , 159 

Melland's  Paper  Powder 159 

Augendre's  Powder 160 

Dynamogen 161 

Hahn's  Powder 162 

Horsley's  Powder 162 

Pertuiset's  Powder 163 

Parone's  Explosive 163 

Petrofracteur 163 

Fuse  Compositions 163 

Davey's  Fuse  Composition 1 64 

Hill's  Fuse  Compositions 164 

Fuse  Composition  for  the  Contract  System 164 

Composition  for  Friction  Fuses 164 

The  Sulphuric-acid  Fuse 164 

Composition  used  in  the  Harvey  Fuse 165 


CONTENTS.  XI 

• 

PAGE 

Composition  for  Fuses  to  be  exploded  by  Frictional  Electricity 165 

English  Priming  Material 165 

Austrian  Priming  Material 166 


LECTURE  X. 

CL  A  SSI  PICA  TION  OF  EXPLOSIVE  COMPOUNDS.    EXPLOSIVE  COMPOUNDS 
OF  THE  NITRO-SUBSTITUTION  CLASS. 

Nitro-substitution  Compounds 167 

Tri-nitro-phenol,  or  Picric  Acid 172 

Borlinetto's  Powder    , 175 

Potassium  Picrate 1 76 

Fontaine's  Powder 176 

Designolle's  Powder 176 

Ammonium  Picrate 177 

Brugere  Powder 178 

Abel's  Powder 178 

Tri-nitro-cresol 180 

Melinite , 181 

Mono-nitrobenzene,  or  Nitrobenzene 182 

Di-nitrobenzene 184 

Tri-nitrobenzene 185 

Bellite 185 

Securite 188 

Nitrotoluene , 189 

Mono-nitronaphthalene 189 

Di-,  Tri-,  and  Tetra-nitronaphthalene , 190 

Volney's  Powders 191 

Favier  Explosives 193 

Emmensite - 195 

Gclbite 199 

Roburite 199 


LECTURE   XI. 

CLASSfFICA  TION  OF  THE  NITRIC  DERIVA  TIVE  CLASS  OF  EXPLOSIVE 
COMPOUNDS. 

Nitric  Esters,     Guncotton. , 202 

Nitric  Esters «„ , 207 

Guncotton. ...,.., 207 

Von  Lenk's  Investigations ., 210 

Von  Lenk's  Process 211 

Abe/s  Improvements  and  Patents 212 

Adoption  of  Guncotton  'n  this  Country  as  a  Service  Explosive 213 


Xll  CONTENTS. 

PAGE 

Chemistry  of  Guncotton 214 

Properties  of  Guncotton , 217 

Decomposition  of  Guncotton . , 220 

Explosive  Effect  of  Guncotton 226 

Nitro-hydrocellulose 230 

Nitrostarch . ...  231 


LECTURE  XIL 

MANUFACTURE  OF  GUNCOTTON  A  T  THE  U.  S.  NAVAL  TORPEDO  STA  TION. 

First  Boiling-tub 23.1 

First  Centrifugal  Washer 235 

First  Drying-room 235 

Picker 236 

Final  Drying-closet 236 

Dipping-,  or  Convejting-room 237 

Dipping-troughs 237 

Acids 238 

Dipping  the  Cotton 239 

The  Lever-press 239 

Digestion-pot 239 

Cooling-troughs 2^0 

Acid-wringer .....    240 

Immersion-tub 241 

Second  or  Guncotton  Boiling-tub 242 

Pulper 242 

Poacher 243 

Stuff-chest 244 

Wagon 244 

Moulding-press 245 

Final  Press. 245 

Storage  of  Guncotton 247 


LECTURE   XIII. 

SERVICE  TESTS  FOR  GUNCOTTON. 

Preparation  of  Unfinished  Guncotton  for  Testing 24*5 

Preparation  of  Finished  Guncotton  for  Testing 250 

Determination  of  Moisture  in  Guncotton 250 

Determination  of  Ash  of  Guncotton 251 

Test  for  the  Presence  of  Free  Acid 251 

Heat  or  Stability  Test 251 

Apparatus  and  Materials  required  for  the  Heat  Test 252 

How  to  make  the  Heat  Test 255 


CONTENTS.  Xlll 

PAGE 

Nitrogen  Test. 256 

Solubility  Test 259 

Test  for  Unconverted  Cotton 261 

Determination  of  Alkaline  Substances 261 

Determination  of  the  Temperature  of  Ignition 261 


LECTURE  XIV. 

NITRIC  ETHERS-NITROGLYCERINE. 

Nitroglycerine 263 

Chemistry  of  Nitroglycerine 266 

Proportions  of  the  Acid  Mixture 270 

Process  of  Nitration 271 

Manufacture  of  Nitroglycerine 271 

Acid  Tank 272 

Glycerine  Tank 272 

The  Converter 272 

Injectors 273 

First  Separator 274 

First  Washing- vat 276 

Second  Washing-vat , 276 

Filtering  Apparatus , 277 

Storage-tank 278 

Discharge-tanks   278 

Denitrification  Apparatus 279 

Process  employed  by  the  French  Government  at  their  Works  at  Vonges. ..  279 

The  Yield  of  Nitroglycerine  from  the  Various  Processes 281 

Properties  of  Nitroglycerine 282 

How  to  thaw  Nitroglycerine  and  its  Compounds 284 

How  to  fire  Nitroglycerine 287 

Decomposition  of  Nitroglycerine 287 

The  Use  of  Nitroglycerine  in  Blasting 289 

Tests  for  Nitroglycerine    291 

Tests  for  the  Presence  of  Free  Acid 292 

Stability  or  Heat  Test  for  Nitroglycerine 292 

Nitrogen  Test 292 

Explosive  Effect  of  Nitroglycerine 293 

LECTURE  XV. 

GUN  COTTON  BLASTING-POWDERS   AND   DYNAMITES. 

Tonite,  or  Tonite  Powder 296 

Potentite 297 

Abel's  Guncotton  Powder 297 

Dynamite .• 297 


XIV  CONTENTS. 

PAGE 

Manufacture  of  Dynamke  No.  I 299 

Properties  of  Dynamite •, 302 

Dynamite  with  an  Active  Base 304 

Dynamite  with  a  Combustible  Base — Carbodynamite 305 

Dynamite  with  an  Explosive  Base 306 

Dynamite  with  a  Nitrate  Mixture  Base 306 

Dynamite  No.  2    306 

Dynamite  with  a  Chlorate  Mixture  Base 307 

Vigorite 307 

Dynamite  with  a  Nitro-substitution  Product  Base 307 

Castellanos  Powder 307 

Dynamite  with  a  Nitric  Derivative  Base 307 

Explosive  Gelatine,  or  Blasting  Gelatine 308 

Properties  of  Explosive  Gelatine 309 

Military  Explosive  Gelatine 310 

Gelatine  Dynamite 311 

Forcite 312 

Tests  for  Dynamite - 312 

Separation  of  the  Nitroglycerine  from  the  Base 312 

Tests  for  Free  Acid  in  Dynamite 313 

Stability  and  Nitrogen  Tests  for  Dynamite .......   313 

Stability  Test  for  Explosive  Gelatine  and  Gelatine  Dynamite   313 

Liquefaction  Tests  for  Explosive  Gelatine  and  Gelatine  Dynamite 313 

Outline  Scheme  for  the  Analysis  of  Nitroglycerine  Preparations 315 

Suggestions  on  the  Analysis  of  Nitroglycerine  Powders 317 


LECTURE   XVI. 
SMOKELESS  POWDERS. 

Manufacture  of  Smokeless  Powder 324 

Properties  of  Smokeless  Powders 327 

Tests  for  Smokeless  Powders   329 

U.  S.  Naval  Smokeless  Powder 330 

Process  of  Manufacture 330 

Poudre  B    332 

Poudre  BN 333 

Troisdorf  Powder 334 

Normal  Powder 335 

W.-A.  Powder 335 

Properties  of  W.-A.  Powder 335 

Cordite 336 

The  Manufacture  of  Cordite 337 

Properties  of  Cordite 338 

Ballistite 339 

Maxim  Powder 34° 

Wetteren  Powder 342 


CONTENTS.  XV 

PAGE 

Leonard  Powder 342 

Rifleite 343 

Indurite 343 


LECTURE   XVII. 

9 

EXPLOSIVES  OF   THE  SFRENGEL    CLASS. 

Rack-a-Rock 347 

Hellhoffite 349 

Oxonite 350 

Panclastite 351 

Romite 352 

Practical  Value  of  Sprengel  Explosives 353 

LECTURE   XVIII. 

FULMINATES,   AMIDES,   AND  SIMILAR    COMPOUNDS. 

Chemical  Constitution  of  the  Fulminates 355 

Mercury  Fulminate 355 

Manufacture  of  Mercury  Fulminate 357 

Properties  of  Mercury  Fulminate. 358 

Percussion-caps  and  Detonators 360 

Silver  Fulminate 362 

Nitrogen  Chloride  or  Chloramide 364 

Nitrogen  Iodide  or  lodoamide ....   366 

Nitrogen  Bromide  or  Bromamide 367 

Nitrogen  Fluoride  or  Fluoramide , 368 

Silver  Amine 368 

Copper  Amine  or  Cupricamine 368 

Nitrogen  Sulphide , 368 

LECTURE   XIX. 

MA NIPULA  TION,   STORA  GE;  A ND  TRA NSPOR  TA  TION  OF  HIGH  EXPLOSIVES. 

Precautions  to  be  observed  in  Handling  High  Explosives 371 

Manipulation  of  High  Explosives  in  preparing  a  Charge 373 

How  to  make  a  Dynamite  Cartridge 373 

How  to  prepare  a  "  Primer  "  to  be  fired  by  means  of  a  "  Time-fuse  ".....   373 

How  to  fire  Dynamite  Cartridges  by  Electricity 375 

Connecting-  or  Leading-wires 377 

Igniting  Apparatus 378 

Precautions  to  be  observed  in  firing  High  Explosives  by  Electricity 380 

Precautions  to  be  observed  in  loading  Shell  and  Torpedoes 381 


XVI  CONTENTS. 


Storage  of  High  Explosives 382 

Transportation  of  H igh  Explosives 386 


LECTURE   XX. 

THE  APPLICATION  OF  HIGH  EXPLOSIVES  FOR  MILITARY  PURPOSES. 

Conditions  to  be  fulfilled  by  a  Military  Explosive 388 

Felling  Trees 389 

Destruction  of  Wooden  Beams 390 

Destruction  of  Iron  and  Steel  Beams 390 

Demolition  of  Bridges 391 

Demolition  of  Doors 392 

Destruction  of  Railway  Tracks 392 

Destruction  of  Artillery  Material 392 

Removal  of  Temporary  Obstructions  in  Waterways 393 

Relative  Force  of  Explosives 394 

Champion's  Experiments  with  High  Explosives  during  the  Franco-Prussian 

War 395 


LECTURE  XXI. 

THE   USE   OF  HIGH  EXPLOSIVES  IN  SHELL. 

Experiments  with  Shell  charged  with  Guncotton 401 

Experiments  with  Shell  charged  with  Nitroglycerine 405 

Experiments  with  Shell  charged  with  Dynamite 406 

Experiments  with  Shell  charged  with  Explosive  Gelatine 408 

Experiments  with  Shell  charged  with  Hellhoffite 409 

Experiments  with  Shell  charged  with  Melinite 410 

LECTURE  XXII. 

EXPLOSION  BY  INFLUENCE,   OR  SYMPATHETIC  EXPLOSION. 

Explosion  by  Influence,  or  Sympathetic  Explosion 412 

Abel's  Investigations 413 

Abel's  Theory  of  Synchronous  Vibrations 414 

Investigations  of  Champion  and  Pellet 414 

Berthelot's  Investigations 415 

Berthelot's  Theory 417 

Threlfall's  Investigations 420 

Threlfall's  Theory 423 


LECTURES  ON  EXPLOSIVES. 


LECTURE    I. 

GENERAL   CONSIDERATIONS  AFFECTING   EXPLOSIONS  AND 
EXPLOSIVES. 

Explosive  Reactions. — All  chemical  changes,  whether  of 
combination  or  decomposition,  are  called  reactions. 

Reactions  take  place  in  or  between  molecules.  The  same 
atoms  are  found  after  a  reaction  as  were  present  before,  but 
differently  arranged  or  united,  forming  molecules,  different 
from  those  which  entered  into  the  reaction.  The  reaction, 
then,  is  a  change  in  the  manner  in  which  the  attractions  or 
affinities  of  the  atoms  are  exerted.  The  operations  of  these 
attractions  are  governed  by  the  circumstances  under  which 
they  are  exercised.  Then,  in  order  to  produce  any  desired 
results,  certain  necessary  conditions  must  be  fulfilled. 

These  conditions  vary  between  extreme  limits.  Thus,  in 
one  compound,  the  attractions  which  bind  together  its  parts 
may  be  so  feebly  exercised  that  the  slightest  change  in  its 
surrounding  circumstances  will  bring  about  its  decomposition, 
while  to  reverse  those  of  another  compound  may  require  that 
the  most  powerful  agencies  should  be  exerted  for  a  long  time. 

Again,  compounds  which  are  stable  at  the  ordinary 
temperature  may  be  broken  up  when  moderately  heated,  or 
reactions  which  occur  at  the  ordinary  pressure  may  be  entirely 
altered  if  the  same  materials  are  brought  together  at  a  differ- 
ent pressure. 


2  LECTURES   ON  EXPLOSIVES. 

Reactions  may  go  on  rapidly  or  slowly,  and  be  accom- 
panied by  evolution  of  gas,  heat,  light,  electricity,  etc. 
When  these  accompaniments  are  of  a  certain  kind  explosive 
effect  results,  and  we  have  explosive  reactions;  but  such 
chemical  changes  are  governed  by  the  same  laws  as  all 
reactions. 

The  term  explosion  may  be  considered  synonymous  with 
explosive  reaction,  and  may  therefore  be  defined  as  a  chemical 
reaction  causing  the  sudden  or  extremely  rapid  formation  of 
a  very  great  volume  of  highly  expanded  (or  heated)  gas.  This 
development  of  expansive  force  characterizes  all  explosives, 
and  any  satisfactory  explanation  of  the  phenomena  attending 
an  explosion  involves  the  consideration  of  the  chemical  and 
physical  conditions  prevailing  before,  during,  and  subsequent 
to  the  reaction. 

The  Chemical  Composition  of  Explosives. — Provided 
the  explosive  contain  sufficient  oxygen  to  convert  all  the 
elements  involved  into  their  most  stable  compounds,  or,  as 
more  commonly  expressed,  to  produce  complete  combustion, 
the  products  of  explosion  may  be  predicted.  This  is  also 
true  of  certain  binary  compounds,  but  in  the  case  of  ternary 
compounds,  and  substances  deficient  in  oxgyen,  the  products 
of  explosion  not  only  cannot  be  predicted,  but  will  vary  with 
all  the  circumstances  and  conditions  of  explosion,  such  as  the 
method  of  producing  explosion,  temperature,  pressure,  expan- 
sion, etc.,  and  must  be  determined  in  each  instance  by  careful 
analysis. 

In  every  explosion,  however,  the  products  of  the  reaction 
are  formed  strictly  according  to  the  chemical  laws  governing 
the  affinities  of  the  several  elements,  and  were  it  not  for 
extraneous  circumstances  these  products  would  correspond 
to  those  due  to  the  maximum  heat  evolved. 

The  Origin  of  Explosive  Reactions. — Explosive  reac- 
tions may  be  brought  about  in  several  ways.  Generally 
speaking,  anything  that  will  cause  the  ignition  of  a  combus- 
tible body  will,  when  applied  to  an  explosive,  cause  an 
explosive  reaction,  or  explosion.  In  other  words,  such  reac- 


GENERAL    CONSIDERATIONS.  3 

tions  originate  in  heat,  each  explosive  substance  having  a 
specific  exploding  point  to  which  the  temperature  of  one  or 
more  of  its  molecules  must  be  raised  before  the  reaction 
resulting  in  the  decomposition  of  the  entire  mass  can  result. 

The  heating  of  the  initial  molecule  to  the  exploding  point 
of  the  substance  is  not  of  itself  sufficient  to  cause  the  explo- 
sion of  the  entire  mass,  but  this  temperature  must  be  trans- 
ferred without  loss  by  radiation,  conduction,  expansion,  etc., 
to  the  adjacent  molecules  throughout  the  substance. 

This  property,  possessed  by  all  explosives,  involves  the 
question  of  molecular  velocity,  which  must  not  be  confounded 
with  the  rapidity  of  propagation  of  the  reaction  which  deter- 
mines the  character  of  the  reaction,  whether  simple  combus- 
tion, explosion,  or  detonation.  The  molecular  velocity  of 
explosive  reactions  is  a  function  of  the  temperature,  and  of 
the  condensation  of  the  substance. 

The  following  are  the  principal  methods  of  originating  an 
explosion : 

1.  Contact  with  a  heated  body,  either  solid,  liquid,  or 

gaseous. 

2.  Friction. 

3.  Percussion. 

4.  Concussion. 

5.  Electric  spark. 

6.  Electric  current. 

7.  Thermal  radiations. 

8.  Chemical  changes. 

9.  Physical  changes. 

10.   Chemical  and  physical  changes. 

The  Propagation  of  Explosive  Reactions. — An  explo- 
sive reaction  once  begun  is  propagated  throughout  the  mass 
of  the  substance,  the  phenomenon  being  reproduced  from 
molecule  to  molecule.  The  rapidity  with  which  this  propaga- 
tion proceeds  determines  the  nature  of  the  resulting  phe- 
nomenon, and  varies  from  the  rate  of  ordinary  combustion  to 
the  almost  infinite  velocity  of  detonation.  The  velocity  of 


4  LECTURES   ON  EXPLOSIVES. 

propagation  in  the  case  of  the  explosion  of  gunpowder  has 
been  measured  and  determined  to  vary  with  the  pressure  of 
the  surrounding  gas.  Thus  in  a  vacuum  gunpowder  cannot 
be  exploded,  whereas  in  the  bore  of  heavy  guns  the  velocity 
of  propagation  is  about  13  feet  per  second.  In  the  open  air 
the  same  velocity  is  approximately  4  feet  per  second,  and 
diminishes  with  every  diminution  of  pressure. 

In  the  case  of  "low"  explosives,  the  laws  of  chemical 
action  afford  explanation  of  the  phenomena  resulting  from 
their  decomposition  and  the  propagation  of  the  reaction. 
This  is  not  true,  however,  with  regard  to  the  modern  "  high  " 
explosives,  as  will  be  shown  later. 

The  influence  of  pressure  has  been  alluded  to  in  the  case 
of  gunpowder;  the  rate  of  propagation,  however,  is  subject 
to  other  considerations,  and  may  be  made  to  vary  in  accord- 
ance therewith,  with  the  results  before  mentioned. 

Moreover,  the  same  explosive  may  be  made  to  develop 
any  of  these  phenomena  by  varying  the  physical  or  mechani- 
cal condition  of  the  explosive  itself,  the  external  conditions, 
and  the  method  of  initial  inflammation. 

Influence  of  Physical  or  Mechanical  Condition  of  the 
Explosive. — Many  instances  may  be  given  indicating  the 
influence  of  its  state  upon  the  explosion  of  a  substance. 
Thus  nitroglycerine  at  temperatures  above  40°  F.  is  a 
liquid,  and  in  the  liquid  condition  may  be  violently  exploded 
by  a  fuse  or  exploder  containing  fifteen  grains  of  fulminating 
mercury.  Below  40°  it  freezes  and  cannot  be  so  fired. 

The  advantage  of  dynamite  over  liquid  nitroglycerine  lies 
altogether  in  the  fact  that  the  former  contains  the  explosive 
body  in  another  mechanical  condition,  more  convenient  and 
safer  to  use  than  the  liquid  form. 

The  nitroglycerine  itself  is  the  same  chemically  in  either 
case. 

The  same  mixture  of  charcoal,  sulphur,  and  saltpetre  gives 
a  very  different  effect  if  made  up  into  large  grains  than  if 
made  up  into  small  ones. 

Guncotton    presents    the    most    marked    example    of   the 


GENERAL    CONSIDERATIONS.  5 

effect  of  mechanical  state,  since  it  can  be  prepared  in  so 
many  ift^ays.  If  flame  is  applied  to  loose,  uncompressed  gun- 
cotton,  it  will  flash  off;  if  the  guncotton  is  spun  into  threads 
or  woven  into  webs,  its  rate  of  combustion  may  be  so  much 
reduced  that  it  can  be  used  in  gunnery  or  for  a  quick  fuse ; 
powerfully  compressed  and  wet,  it  burns  slowly;  dry  gun- 
cotton  may  be  exploded  by  a  fulminate  exploder;  wet  gun- 
cotton  requires  an  initial  explosion  of  a  small  amount  of  the 
dry,  etc. 

Influence  of  External  Conditions. — Confinement  is  nec- 
essary to  obtain  the  full  effect  of  all  explosives.  The  most 
rapid  explosion  requires  a  certain  time  for  its  accomplish- 
ment. As  the  time  required  is  less,  the  amount  of  confine- 
ment necessary  is  less.  Then  with  the  sudden  or  violent 
explosives  the  confinement  required  may  be  so  small  that  its 
consideration  may  be  practically  neglected.  For  instance, 
large  stones  or  blocks  of  iron  may  be  broken  by  the  explo- 
sion of  nitroglycerine  upon  their  surfaces  in  the  open  air. 
Here  the  atmosphere  itself  acts  as  a  confining  agent.  The 
explosion  of  the  nitroglycerine  is  so  sudden  that  the  air  is 
not  at  once  moved. 

Again,  chloride  of  nitrogen  is  one  of  the  most  sudden  and 
violent  of  all  explosives.      In  its  preparation  it  is  precipitated 
from  a  watery  liquid,  and  therefore  is,  when  used,  wet  or  cov 
ered  with  a  very  thin  film  of  water. 

This  thin  film  of  water,  not  more  than  YoVo"  °f  an  mcn  in 
thickness,  is  a  necessary  and  sufficient  confinement,  and  if  it  is 
removed  the  explosive  effect  is  much  diminished.  Gunpowder, 
on  the  other  hand,  requires  strong  confinement,  since  its  explo- 
sion is  comparatively  slow.  Thus  in  firing  a  large  charge  of 
gunpowder  under  water,  unless  the  case  is  strong  enough  to 
retain  the  gases  until  the  action  has  become  general,  it  will  be 
broken,  and  a  large  amount  of  the  powder  thrown  out  un- 
burned.  This  is  often  the  case  in  firing  large-grained  powder 
in  heavy  guns.  The  projectile  leaves  the  gun  before  all  the 
powder  has  burned,  and  grains  or  lumps  of  it  are  thrown  out 
uninjured. 


d  i 

M 


O  LECTURES   ON  EXPLOSIVES. 

The  confinement  needed  by  the  slower  explosives  may  be 
diminished  by  igniting  the  charge  at  many  points,  so  that  less 
time  is  required  for  complete  explosion. 

Influence  of  Method  of  Initial  Inflammation. — In  any 
explosive  reaction,  the  mode  of  bringing  about  the  change 
exercises  an  important  influence.  The  application  of  heat, 
directly  or  indirectly,  is  the  principal  means  of  causing  an 
explosion.  Thus,  in  gunnery,  the  flame  from  the  percussion- 
cap  or  primer  directly  ignites  the  charge ;  so  also  a  fine  plati- 
num wire  heated  by  an  electric  current  will  ignite  explosive 
material  which  is  in  contact  with  it.  Friction,  percussion, 
concussion,  produce  the  same  effect  indirectly,  by  the  conver- 
sion of  mechanical  energy  into  heat,  which  is  communicated 
to  the  body  to  be  exploded. 

When  one  explosive  body  is  used  as  a  means  of  firing 
another,  it  may  be  considered  that  the  blow  delivered  by  the 
gas  suddenly  formed  from  the  firing-charge  acts  percussively 
upon  the  mass  to  be  exploded.  The  particles  of  this  gas  are 
thrown  out  with  great  velocity,  but  meeting  with  the  resistance 
of  the  mass  around  them  they  are  checked,  and  their  energy 
is  converted  into  heat.  It  is  found,  however,  that  the  action  of 
explosives  on  one  another  cannot  be  perfectly  explained  in  this 
way. 

If  the  action  were  simply  the  conversion  of  energy  into 
heat,  then  the  most  powerful  explosive  would  be  the  best 
agent  for  causing  explosion.  But  this  is  not  the  case.  Nitro- 
glycerine is  much  more  powerful  than  fulminating  mercury; 
but  fifteen  grains  of  the  latter  will  explode  guncotton,  while 
seventy  times  as  much  nitroglycerine  will  not  do  it. 

Chloride  of  nitrogen  is  much  more  violent  than  fulminat- 
ing mercury,  but  larger  quantities  of  the  former  than  of  the 
latter  must  be  used  to  cause  other  explosions. 

Again,  nitroglycerine  is  fired  with  certainty  by  a  small 
amount  of  fulminating  mercury,  while  with  a  much  larger 
amount  of  gunpowder  the  explosion  is  less  certain  and  feebler. 

In  these  cases  it  is  evident  that  the  fulminating  mercury 
must  have  some  special  advantage,  since  it  produces  the  de- 


GENERAL    CONSIDERATIONS.  7 

sired  effect  more  easily  than  the  others.  It  may  be  considered 
that  the  fulminating  mercury  sets  up  a  form  of  motion  or 
vibration  to  which  the  other  bodies  are  sensitive.  Just  as  a 
vibrating  body  will  induce  corresponding  vibrations  in  others, 
so  the  peculiar  rate  of  motion,  or  wave  of  impulse,  sent  out  by 
fulminating  mercury,  exerts  a  greater  disturbing  influence 
upon  the  molecules  of  certain  bodies  than  that  derived  from 
other  substances. 

An  explosive  molecule  is  unstable  and  very  susceptible  to 
external  influences.  Its  atoms  are  in  a  nicely  balanced  state 
of  equilibrium,  which  is,  however,  more  readily  overturned  by 
one  kind  of  blow  than  another.  The  explosive  molecule  takes 
up  the  wave  of  impulse  of  the  fulminate,  but  the  strain  is  too 
great,  and  its  own  balance  is  destroyed. 

In  addition,  the  explosion  proceeds  very  differently  when 
brought  about  in  this  way  than  when  caused  by  simple  in- 
flammation. When  a  mass  of  explosive  is  ignited  by  a  flame, 
the  action  extends  gradually  through  it ;  but  if  it  is  exploded 
by  a  blow,  acting  in  the  .manner  above  described,  it  is  plain 
that  the  explosion  will  be  nearly  instantaneous  throughout, 
since  the  impulse  will  be  transmitted  through  the  mass  with 
far  greater  rapidity  than  an  inflammation  proceeding  from 
particle  to  particle.  The  explosive  reaction  will  then  proceed 
much  more  rapidly,  and  the  explosive  effect  will  be  much 
sharper,  that  is,  more  violent. 

Combustion,  Explosion,  Detonation. — These  terms  are 
used  to  express  different  phases  of  the  same  reaction,  depend- 
ing almost  altogether  upon  the  velocity  of  propagation  of  the,;//  ' 
explosive  reaction.  This  may  considered  absolutely  true 
with  regard  to  the  first  two  phenomena.  In  the  case  of  com- 
bustion the  reaction  progresses  very  slowly  and  gradually, 
and  can  be  controlled  by  mechanical  means,  such  as  commi- 
nuting the  particles,  etc.,  while  in  the  case  of  explosion  the 
velocity  of  propagation  is  relatively  very  rapid,  and  the  true 
nature  of  the  changes  that  occur  is  frequently  lost  sight  of  on 
account  of  the  rapidity  with  which  the  different  phases  of  the 
phenomenon  succeed  each  other.  There  can  be  no  doubt, 


LECTURES    ON  EXPLOSIVES. 

however,  that  explosion  is  but  a  rapid  form  of  combus- 
tion. 

In  the  case  of  detonation,  the  laws  governing  chemical 
action  fail  to  account  for  all  of  the  phenomena  accompanying 
the  explosive  reaction  in  which  the  time  element  is  reduced 
to  the  •minimum,  and  the  theory  of  thermodynamics  must 
be  applied  in  order  to  afford  a  satisfactory  explanation. 

Thus  in  the  case  of  mercury  fulminate,  which  is  pecul- 
iarly effective  in  provoking  detonation,  the  decomposition  of 
this  substance  is  characterized  by  extremely  rapid  chemical 
transformation  and  intense  local  action.  We  may  assume, 
therefore,  that  the  energy  of  the  initial  shock  produced  lo- 
cally by  this  substance  is  transformed  into  heat  at  the  point 
of  action  which  serves  to  raise  the  temperature  of  the  par- 
ticles (or  molecules)  first  subjected  to  its  action  up  to  their 
point  of  explosive  reaction.  The  sudden  decomposition  of 
these  particles  produces  a  second  shock  more  violent  and 
energetic  than  that  received,  which  is  in  turn  transmitted, 
thus  developing  a  regular  succession  of  shocks  and  decom- 
positions which  is  propagated  throughout  the  entire  mass 
from  particle  to  particle  with  a  velocity  far  greater  than  that 
characterizing  simple  inflammation. 

According  to  this  view,  detonation  is  the  result  of  a  com- 
bination of  true  chemical  and  dynamical  reactions,  neither  of 
which  alone  suffices  to  explain  the  attending  phenomena.  If 
the  transformation  were  due  merely  to  the  mechanical  energy 
of  the  particles  of  gas  liberated  at  the  initial  shock  at  a 
tremendous  velocity  being  converted  into  heat  by  impact 
against  the  mass  of  the  explosive  substance,  then  it  would 
follow  that  the  most  powerful  explosive  would  be  the  best 
detonating  agent ;  that  is,  however,  by  no  means  the  case,  for 
a  few  grains  of  fulminate  of  mercury  in  a  metal  tube  will 
detonate  guncotton,  whereas  nitroglycerine,  although  pos- 
sessed of  more  explosive  force,  will  not  do  so  unless  used  in 
large  quantities.  The  fact  of  its  being  possible  to  detonate 
wet  guncotton  is  also  a  proof  that  the  action  cannot  be  due 
to  heat  alone. 


GENERAL    CONSIDERATIONS.  9 

As  already  stated,  an  explosive  molecule  is  most  unstable, 
certain  very  delicately  balanced  forces  preserving  the  chemi- 
cal and  physical  equilibrium  of  the  compound. 

If  these  forces  be  rapidly  overthrown  in  succession,  we 
have  explosion ;  but  when,  by  a  blow  of  a  certain  kind,  they 
are  instantaneously  destroyed,  the  result  is  detonation.  Just 
as  a  glass  globe  may  withstand  a  strong  blow,  but  be  shat- 
tered by  the  vibration  of  a  particular  note,  so  it  is  considered 
by  some  authorities  that,  in  the  instance  cited,  the  fulminate 
of  mercury  communicates  a  vibration  to  which  the  gun- 
cotton  molecule  is  sensitive,  and  which  overthrows  its  equi- 
librium ;  it  is  not  sensitive  to  the  vibrations  caused  by  nitro- 
glycerine, which  only  tears  and  scatters  it  mechanically. 
Although  the  action  of  detonation  has  been  spoken  of  as 
instantaneous,  and  may  practically  be  so  considered,  yet  a 
certain  infinitesimal  duration  of  time  is  required  for  the 
metamorphosis;  different  substances  possess,  doubtless,  dif- 
ferent rates  of  detonation,  for  we  can  scarcely  conceive  of  a 
mechanical  mixture,  such  as  gunpowder,  being  so  sensitive 
to  the  action  of  the  detonating  impulse  as  a  definite  chemical 
compound,  and  the  rate  even  varies  slightly,  for  the  same 
explosive,  with  its  chemical  state.  It  has  been  shown  by 
means  of  Captain  A.  Noble's  chronoscope  that  compressed 
guncotton,  when  dry,  is  detonated  at  a  velocity  of  from 
17,000  to  18,000  feet  a  second,  or  about  200  miles  a  minute; 
by  using  a  small  primer  of  dry  guncotton  the  same  sub- 
stance in  the  wet  state  may  be  detonated  at  the  increased 
rate  of  from  18,000  to  21,000  feet  a  second,  or  about  240 
miles  a  minute. 

Bodies  Susceptible  of  Detonation. — Some  substances 
seem  always  to  detonate  no  matter  how  fired  (e.g.,  chloride 
of  nitrogen,  the  fulminates,  etc.),  while  others  are  detonated 
or  not  according  to  the  mode  of  firing  (e.g.,  guncotton,  gun- 
powder, etc.). 

Probably  all  explosives  can  be  detonated  if  the  right 
methods  of  doing  so  are  known. 

Guncotton  seems  to  have  a  greater  range  of  susceptibility 


10  LECTURES   ON  EXPLOSIVES. 

to  different  modes  of  firing  than  any  other  explosive  agent. 
It  can  be  made  to  burn  slowly  without  explosion,  and  the 
rapidity  of  its  action  can  be  increased  up  to  the  detonating 
point. 

Nitroglycerine  always  explodes  powerfully,  but  its  effect 
is  much  lessened  when  fired  with  gunpowder. 

Gunpowder  as  ordinarily  used  is,  of  course,  not  deto- 
nated, as  the  violent,  sudden  effects  of  detonation  would  be 
undesirable.  For  other  purposes  (e.g.,  torpedoes,  blasting, 
etc.)  it  would  be  a  great  advantage  if  it  could  be  made  to 
give  more  violent  explosive  effects  by  a  peculiar  mode  of 
firing.  It  has  been  demonstrated  that  this  can  be  done, 
although  the  best  mode  of  doing  it,  or  whether  detonation  is 
actually  accomplished,  is  not  known.  Experiments  in  this 
direction  can  har.dly  fail  to  give  valuable  results. 

Probably  a  mechanical  mixture  like  gunpowder  can  never 
be  brought  by  any  mode  of  firing  to  approach  as  near  to  a 
perfect  detonation  as  the  chemical  substance  nitro-glycerine 
or  guncotton ;  but  even  if  not  detonated,  better  effects  for 
certain  uses  may  be  obtained  from  it  if  the  proper  means 
are  used. 

Roux  and  Sarrau  have  recently  published  some  interest- 
ing results  of  experiments  on  the  different  explosive  effects 
produced  by  some  bodies  by  certain  modes  of  firing.  They 
divide  explosions  into  two  kinds:  detonations,  or  explosions 
of  the  first  order,  and  simple  explosions,  or  explosions  of  the 
second  order.  Simple  explosions  are  produced  either  by 
direct  inflammation  or  by  a  small  charge  of  gunpowder. 
Detonations  are  obtained  from  nitroglycerine,  guncotton, 
picric  acid,  and  certain  picrates  by  exploding  with  fulmi- 
nating mercury. 

Fulminating  mercury,  they  state,  does  not  detonate  gun- 
powder; but  if  the  exploding  charge  is  a  small  amount  of 
nitroglycerine,  itself  detonated  by  fulminate,  an  explosion  of 
the  first  order  is  obtained  from  gunpowder.  The  relative 
effects  were  approximately  measured  by  determining  the 


UNFV 

^ 

GENERAL    CONSIDERATIONS.  II 

quantities  necessary  to  rupture  small  cast-iron  shells  of  nearly 
equal  strength. 

The  following  are  among  the  results  given,  showing  the 
great  difference  in  force  of  the  two  kinds  of  explosion : 

Explosive  Force. 

First  Order,    Second  Order, 

or  or 

Inflammation.     Detonation. 

Nitroglycerine 4.80  10.13 

Guncotton  (compressed) 3.00  6.46 

Picric  acid 2.00  5.50 

Potassium  picrate 1.80  5.30 

Gunpowder 1 .00  4-34 

There  is  for  each  explosive  about  a  certain  amount  and 
kind  of  force  required  to  effect  detonation,  which  must  not 
be  materially  departed  from. 

If  the  exploder  is  too  weak,  inflammation  or  a  feeble  ex- 
plosion only  will  result ;  if  too  heavily  charged,  it  is  more 
likely  to  scatter  or  disintegrate  the  material  acted  upon  than 
to  explode  it.  There  is  also  a  relation  between  the  mass  of 
the  explosive  and  the  charge  of  the  detonator  which  must  be 
observed.  This  relation  is  more  marked  with  some  explosives 
than  with  others.  Thus,  nitroglycerine  is  a  body  easily  deto- 
nated, and  the  same  amount  of  fulminate  seems  to  fire  equally 
well  all  usual  quantities.  If  a  single  particle  is  detonated, 
the  action  quickly  extends  through  the  whole  mass. 

Other  substances,  less  easily  detonated,  require  that  as 
the  mass  is  increased  the  force  applied  shall  be  increased,  so 
that  all  the  particles  shall  receive  -a  sufficient  blow,  otherwise 
only  a  part  will  be  detonated. 

PRODUCTS  OF  EXPLOSIVE  REACTIONS. 

The  products  of  the  reaction  which  characterizes  an  ex- 
plosion are,  first,  gas  or  gases  rapidly  formed,  and,  secondly, 
heat  evolved  which  serves  to  expand  and  further  increase  the 
volume  of  gas. 


12  LECTURES   ON  EXPLOSIVES. 

The  effects  produced  by  an  explosion  are  made  evident 
by  the  pressure  exerted  by  the  gases,  and  by  the  work  ac- 
complished. 

The  first  effect  is  due  to  the  gas  or  gases  evolved,  and 
[depends  upon  their  volume  and  pressure  ;  the  second,  how- 
lever,  is  a  function  of  the  heat  liberated,  which  measures  the 
Energy  developed. 

To  define  the  force  of  an  explosive,  however,  there  is 
still  another  factor  to  be  considered,  and  that  is  the  rapidity 
of  the  reaction  ;  these  three  elements,  the  volume  of  gas,  the 
quantity  of  heat,  and  the  rapidity  of  the  reaction,  afford  all 
the  data  necessary  to  calculate  the  force  of  an  explosive. 

The  Volume  of  Gas  Evolved.  —  The  volume  of  gas 
evolved  in  any  explosive  reaction  may  be  measured  directly 
by  means  of  various  apparatus,  based  upon  either  static  or 
dynamic  laws.  The  apparatus  involving  the  static  method 
are  known  as  pressure-gauges,  such  as  Rumford's,  Rodman's 
cutter  gauge,  Uchatins'  eprouvette,  and  various  crusher 
gauges. 

The  dynamic  method  employs  the  various  ballastic  pendu- 
lum apparatus,  crushing  tests,  etc. 

These  methods  will  be  referred  to  later. 

The  volume  of  gas  may  also  be  closely  calculated,  but 
only  when  they  are  simple  and  stable  products,  such  calcula- 
tions being  made  at  o°  C.  and  760  mm.  Thus  let  it  be  re- 
quired to  determine  the  volume  of  gas  evolved  by  one  molu- 
gram*  of  nitroglycerine.  The  explosive  reaction  of  nitro- 
glycerine may  be  represented  by  the  equation 


jf 


C,H  A(NO,)8  =  3CO,  +  2*H,0  +  iJN,  +  JO,. 

By  weight, 

227=  132  +  45  +42  +  8. 
By  volume, 


*  A  molugram  is  the  weight  of  a  substance  (expressed  in  grammes) 
equivalent  to  its  molecular  weight. 


GENERAL    CONSIDERATIONS.  13 

The  weights  of  the  several  products  of  the  above  reactions 
are  calculated  by  multiplying  their  specific  gravities  by  the 
weight  of  one  litre  of  hydrogen  at  o°  C.  and  760  mm. 
(0.0896  gm.).  Thus, 

One  litre  of  CO2   =  22  X  .0896  =  1.9712  gm. 
«      «      «i  H^O  =    9x      "      =0.8064     " 
«i      <•<      «  N2      =  14  X      "      =1.2544     " 
"     «<      «  O2      =i6x      "      =1.4336     " 

The  volume  of  permanent  gases  at  o°  and  760  mm.  is 
constant,  and,  assuming  the  gramme  as  the  unit  of  mass,  is 
found  to  be  22.32  litres.  Thus, 

Vol.  of  44  gm.  of  CO2   at  o°  C.  and  760  mm.  =  =  22.32  litres. 

18 

=  22.32 


'    18    ' 

'  H20  " 

0.8064 
«  «  <«  28 

1.2544 
«  «,  «,  32 

=  22.32 
1.4336  =22'32     " 

Therefore, 

132  gm.  of  CO2  at  o°  C.  and  760  mm.  =  22.32  X  3    =  66.96  litres. 
45    "     "  H20  "      "       "       "       "=22.32X2^=55.80     " 
42    "     "     N2    "      ••       "       "       tf    =22.32X1^  =  33-48     " 
8    "     "     O2    "      "        "       "       '*    =  22.32  X    i=    5-58     " 


161.82     " 

Therefore  one  molugram,  or  227  gvm.,  of  nitroglycerine  when 
exploded  produces  161.82  litres  of  gas  at  o°  C.  and  760  mm. 
To  determine  the  volume  of  gas  at  the  temperature  of  explo- 
sion, we  simply  apply  the  Law  of  Charles,*  thus: 

V\  V  ::  T:  T',     or     V  =  F^-', 

*  According  to  the  Law  of  Charles,  the  volume  of  any  gas  varies  di- 
rectly as  its  temperature  on  the  Absolute  Scale,  provided  the  pressure 
remains  constant.  Knowing  the  temperature  on  the  Centigrade  Scale,  the 
corresponding  temperature  on  the  Absolute  Scale  is  obtained  by  adding 
273  to  the  degrees  C. 


14  LECTURES   ON  EXPLOSIVES. 

in  which  V    represents  the  original  volume ; 
V  represents  the  new  volume; 

T    represents  the  original  temperature  on  the  abso- 
lute scale ; 
T'  represents  the  new  temperature  on  the  same  scale. 

In  the  present  case  T'  —  6001°. 
Therefore  substituting,  we  have 

161.82  X  6001 
V  = —      -  =  3557  litres. 

Or  at  the  temperature  of  explosion  one  molugram  of  nitro- 
glycerine produces  3557  litres  of  permanent  gas.  The  vol- 
ume of  gas  thus  calculated  when  measured  by  the  apparatus 
referred  to  is  generally  recorded  in  terms  of  the  pressure 
exerted,  and,  notwithstanding  the  great  difficulties  attending 
such  investigations,  the  calculated  and  recorded  results  have 
been  found  to  agree  within  reasonable  limits. 

Thus  M.  Berthelot  measured  by  means  of  his  crusher 
gauge  the  pressure  developed  by  the  explosion  of  10  gm.  of 
mercury  fulminate,  and  found  it  to  be  1183  kgm.  per  sq.  cm. 
By  calculation  it  should  be  1293  kgm.  per  sq.  cm.  In  the 
case  of  nitrogen  sulphide  (by  the  same  investigator)  the 
result  was  as  1703  to  1707  kgm.  per  sq.  cm. 

Temperature  of  Explosion. — The  temperature  of  explo- 
sion which  serves  to  expand  these  gases  may  also  be  meas- 
ured directly  by  means  of  the  calorimeter,  or  calculated 
theoretically. 

The  measurement  of  such  high  temperatures  as  obtain  at 
the  instant  of  explosion,  however,  is  attended  with  so  many 
difficulties  that  that  method  is  limited  practically  to  a  very 
few  special  experimenters.* 

*  M.  Berthelot  has  performed  the  most  notable  experiments  in  this 
direction,  and  the  results  of  his  labors  afford  the  most  complete  and  relia- 
ble data  to  be  had  on  the  subject.  These  results  will  be  found  tabulated 
in  his  work  "  Sur  la  force  des  matieres  explosives  d'apres  la  Thermo- 
chimie." 


GENERAL    CONSIDERATIONS.  1 5 

The  temperature  of  an  explosive  reaction  may  be  calcu- 
lated by  the  formula  » 

WC 

~~  W&+  W&+  ^,5,  + etc.' 
in  which    T  =  the  temperature  sought; 

W '=  the  weight  of  explosive  used; 
C  —  the  calorific  power  of  the  explosive  at  1 00°  C; 
WiyW^,W3  =  the  weights  of  the  products  of  explosion ; 
£» ,  5, ,  S8  =  the    specific    heats  *    of  the   products  of  ex- 
plosion. 

Thus  let  it  be  required  to  calculate  the  temperature  de- 
veloped by  the  explosive  reaction  of  one  gramme  of  nitro- 
glycerine. 

The  equation  representing  such  reaction  may  be  written 
as  follows : 

C,H503(N02)3  =  3C02  +  2iH20  +  iiN.  +  iOa. 

According  to  Berthelot,  the  calorific  power  of  nitro- 
glycerine is  356,500  cal.f  Substituting  in  the  formula  above 
this  value  for  C,  and  for  WlSl ,  W9S9 ,  WZSZ ,  etc.,  their  values 
as  follows : 

=  132  X  .2169  =  28.63 
=  45  X  .4805  =  24.63 
=  42  X  .2438  =  10.24 
=  8  X  .2175  =  1.74 


62.24 
we  have 

^^56500 

62.24 

*  The  specific  heat  of  a  substance  is  the  amount  of  heat  required  to 
raise  one  gramme  of  the  substance  through  i°  C. 

f  A  calorie  (cal.)  is  £he  quantity  of  heat  required  to  raise  one  gramme 
of  water  o°  to  i°  C. 

A  large  calorie  .(Cal.)  is  the  quantity  of  heat  required  to  raise  one 
kilogramme  of  water  from  o°  to  i°  C. 


1 6  LECTURES   ON  EXPLOSIVES. 

This  temperature  is  theoretically  independent  of  the  con- 
taining vessel  in  which  the  reaction  takes  place,  provided 
this  reaction  remains  unchanged. 

Effect  of  Dissociation. — The  calculated  temperature  of 
an  explosive  reaction  is  as  a  general  rule  greater  than  the 
actual  temperature.  In  the  first  place  the  specific  heat  of 
gases  under  pressure  is  not  constant,  but  increases  with  the 
temperature,  so  that  an  equal  quantity  of  heat  applied  to 
compressed  gases  produces  a  less  rise  of  temperature  than 
would  result  from  constant  specific  heats  of  the  same  gases  at 
normal  pressure,  which  is  the  assumption  in  these  calculations. 

In  the  second  place,  the  phenomenon  of  dissociation  must 
be  considered  in  connection  with  these  reactions.  All  cal- 
culations as  to  the  temperature  of  explosion  are  based  upon 
the  products  of  the  reaction  after  partial  cooling,  whereas  it 
is  more  than  probable  that  at  the  instant  of  explosion  the 
temperature  may  be  so  excessive  as  to  determine  much  sim- 
pler products,  or  even  to  dissociate  the  mass  into  its  constit- 
uent elements.  Thus  the  resulting  polysulphide  may  have 
been  separated  into  sulphur  and  monosulphide  at  the  tem- 
perature of  explosion  and  recombined  during  the  process  of 
Cooling;  so  also  the  separation  of  water-gas  into  its  elements 
of  hydrogen  and  oxygen. 

Dissociation  is  attended  with  absorption  of  heat,  and  is 
therefore  characterized  by  diminution  of  pressure  of  the  gas- 
eous system.  It  moreover  exercises  its  influence  at  the  first 
period  of  expansion,  and  affects  the  maximum  effort  devel- 
opable by  the  explosive.  As  the  expansion  progresses,  as  in 
acting  upon  a  projectile  in  the  bore  of  a  gun,  the  temperature 
of  the  gases  decreases,  and  the  elements  enter  more  com- 
pletely into  combination  with  the  formation  of  more  compli- 
cated products. 

The  importance  of  this  factor  in  influencing  an  explosive 
reaction  must  not  be  overlooked,  and  has  been  made  an 
object  of  special  investigation  by  those  who  seek  to  offer  a 
coherent  explanation  of  all  the  phenomena  incident  to  an 
explosion. 


GENERAL    CONSIDERATIONS.  17 

Potential  Energy  of  Explosives. — The  quantity  of  heat 
liberated  by  an  explosive  is  fixed  and  constant,  and  can  be 
calculated  only  when  the  substance  undergoes  complete  com- 
bustion. In  the  case  of  incomplete  combustion  the  products 
of  decomposition  will  vary  (as  stated  before)  with  the  initial 
method  of  inflammation,  pressure,  and  other  attending  circum- 
stances, and  the  heat  cannot  be  calculated.  Since,  however, 
the  heat  liberated  measures  the  maximum  work  that  can  be 
developed  by  an  explosive  under  atmospheric  pressure,  if  this 
quantity  of  heat  be  multiplied  by  425  (its  mechanical  equiva- 
lent) the  resulting  product  will  represent  the  potential  energy 
of  the  explosive,  expressed  in  kilogrammetres. 


LECTURE   II. 

PRINCIPLES  OF  THERMOCHEMISTRY  AS  APPLIED  TO  EX- 
PLOSIVES, AND  THE  CLASSIFICATION  AND  COMPOSI- 
TION OF  EXPLOSIVES. 

THE  scope  of  this  work  does  not  admit  of  more  than 
reference  to  such  of  the  principles  of  thermochemistry  as 
are  necessary  to  a  proper  understanding  of  the  theory  of 
explosives  and  of  the  rationale  of  explosive  reactions.  For 
those  who  desire  to  enter  more  fully  into  this  important 
branch  of  the  subject  of  explosives,  reference  may  be  had  to 
the  investigations  of  M.  Berthelot. 

As  the  result  of  these  investigations,  M.  Berthelot  bases 
thermochemistry  upon  three  fundamental  principles,  molecu- 
lar work,  the  calorific  equivalence  of  chemical  transformations, 
and  maximum  work. 

Molecular  Work. — This  principle  is  stated  as  follows: 
The  quantity  of  heat  liberated  in  any  reaction  measures  the 
sum  of  chemical  and  physical  work  accomplished  in  this 
reaction. 

Whence  it  follows  that  the  heat  liberated  in  any  reaction 
is  precisely  equivalent  to  the  amount  of  work  necessary  to 
restore  the  bodies  to  their  primitive  or  initial  state,  this  work 
being  both  chemical  and  physical. 

Until  comparatively  recently  it  was  assumed  that  every 
synthetical  chemical  reaction  was  attended  with  evolution  of 
heat,  and  that  whenever  the  elements  composing  a  body  were 
separated  by  decomposition  heat  was  absorbed. 

This  error  has  been  corrected,  and,  depending  upon  the 
principle  resulting  therefrom,  reactions  are  classified  as  exo- 

18 


THERMOCHEMISTRY  AND    CLASSIFICATION.  1 9 

thermal  or  endothermal  according  as  heat  is  liberated  or 
absorbed.  Thermochemistry  further  divides  substances  into  : 
two  corresponding  classes,  exotherms  and  endotherms.  An 
exotherm  is  a  substance  which  evolves  heat  during  formation. 
An  endotherm  is  a  substance  which  absorbs  heat  during  forma- 
tion. This  division  of  explosive  substances  becomes  of  great 
importance  in  calculating  the  heat  developed  by  an  explosive 
reaction. 

In  a  general  sense  the  amount  of  heat  absorbed  in  the 
formation  of  an  explosive  measures  its  stability,  although 
all  endothermous  substances  are  not  necessarily  unstable. 

In  accounting  for  the  energy  developed  by  any  explosive 
reaction,  Berthelot  considers  merely  the  initial  and  final  states, 
and  the  quantity  of  heat  liberated  is  the  algebraic  sum  of  the 
heats  involved,  which  may  be  positive  or  negative  according 
to  circumstances.  It  is  necessary  to  take  into  consideration, 
however,  not  only  the  heat  of  formation  of  the  explosive  and 
that  of  decomposition,  which  at  extremely  high  temperatures 
involves  dissociation,  as  already  stated,  but  the  recombination 
of  the  atoms  of  the  several  elements  to  form  molecules  enters 
as  an  important  factor.  Thus  in  the  explosion  of  nitrogen 
trichloride  the  great  energy  developed  may  be  accounted  for 
by  the  fact  that,  although  the  heat  of  formation  of  the  sub- 
stance amounts  to  38,100  cal.,  the  separation  of  the  dissimilar 
atoms  of  N  and  Cl  may  be  accompanied  by  the  absorption  of 
an  equal  or  greater  quantity  of  heat,  which  serves  to  neutral- 
ize the  heat  of  formation,  leaving  the  heat  evolved  by  the 
combination  of  the  similar  atoms  of  N  and  Cl  in  the  forma- 
tion of  the  molecules  of  nitrogen  and  chlorine  available  for 
the  development  of  energy. 

The  Calorific  Equivalence  of  Chemical  Transforma- 
tions.— This  is  also  termed  the  principle  of  the  initial  and 
final  state,  and  is  stated  as  follows:  "If  a  system  of  simple 
or  compound  bodies,  under  given  conditions,  undergo  physi- 
cal or  chemical  changes  capable  of  bringing  it  to  a  new  state 
without  giving  rise  to  any  mechanical  effect  exterior  to  the 
system,  the  quantity  of  heat  liberated  or  absorbed  by  the 


2O  LECTURES   ON  EXPLOSIVES. 

effect  of  these  changes  depends  solely  on  the  initial  and  final 
states  of  the  system.  It  is  the  same  whatever  the  nature  or 
the  sequence  of  the  intermediate  states  may  be." 

An  explanation  of  this  principle  involves  that  of  molecular 
work  and  the  principle  of  energy,  while  it  gives  rise  to  several 
important  subordinate  theorems. 

It  is  particularly  applicable  to  explosive  reactions  giving 
rise  to  unknown  or  but  partially  known  products,  and  to  the 
products  of  incomplete  combustion.  Thus  it  is  only  necessary 
to  explode  the  substance,  first  in  pure  oxygen,  and  then  in 
nitrogen,  and  to  measure  the  heat  liberated  in  each  case. 
The  difference  between  these  figures  will  express  the  heat  of 
combustion  of  the  products  of  the  second  reaction,  which 
measures  the  energy  available  in  total  combustion. 

Another  important  corollary  of  this  principle  establishes 
the  difference  between  the  heat  of  combustion  by  free  and 
combined  oxygen. 

As  a  result,  the  imperfectly  understood  action  of  certain 
agents  entering  into  the  composition  of  explosives,  known  as 
oxidizers,  is  clearly  established. 

They  are  no  longer  to  be  regarded  merely  as  magazines 
of  oxygen,  for  we  know  that  the  oxygen  forming  a  part  of 
their  composition  has  lost  a  part  of  its  energy  equivalent  to 
the  heat  of  initial  combination,  and  we  must  distinguish 
between  the  entire  amount  of  oxygen  contained  and  the 
amount  available  for  oxidation.  On  the  other  hand,  how- 
ever, it  may  happen  that  the  combined  oxygen  may  liberate 
more  heat  than  the  free  element,  as  in  the  case  of  potassium 
chlorate. 

Maximum  Work. — "  Every  chemical  change  effected 
without  the  intervention  of  a  foreign  energy  tends  towards 
the  production  of  the  body  or  of  the  system  of  bodies  liberat- 
ing the  most  heat." 

This  principle  results  from  the  observation  that  the  sys- 
tem which  has  liberated  the  greatest  possible  amount  of  heat 
no  longer  possesses  in  itself  the  requisite  energy  to  effect 
further  decomposition  or  transformation,  but  must  invoke  the 


THERMOCHEMISTRY  AND    CLASSIFICATION.  21 

aid  of  extraneous  force  or  energy.  This  force  or  energy  may 
assume  one  of  the  many  forms  of  physical  agents  or  of 
chemical  reactions. 

This  third  principle  was  deduced  by  M.  Berthojot  almost 
entirely  from  the  experimental  study  of  the  phenomena  of 
combination  and  decomposition  ("Essai  de  Mecanique  Chi- 
mique  "),  and  by  its  application  all  explanation  of  these  phe- 
nomena is  based  upon  the  accepted  physical  and  mechanical 
theories  of  maximum  work  effected  by  molecular  action. 

In  all  subsequent  calculations  reference  may  be  had  to 
the  exhaustive  tables  contained  in  the  work  on  thermo- 
chemistry by  the  same  author. 


CLASSIFICATION  AND   CONSTITUTION   OF   EXPLOSIVES. 

Although  the  classification  of  explosives  by  Berthelot  is 
of  little  practical  value,  it  serves  to  show  the  unlimited  nature 
of  the  subject  from  an  abstract  point  of  view. 

According  to  Berthelot  ("Sur  la  force  des  matieres  explo- 
sives") every  system  of  bodies  capable  of  developing  perma- 
nent gases,  or  substances  which  assume  the  gaseous  state  by 
reason  of  a  reaction,  such  as  water  above  100°  C.,  mercury 
above  360°,  etc.,  can  constitute  an  explosive  agent. 

Gases  themselves  become  explosive  if  they  are  com- 
pressed beforehand,  or  rather  if  their  volume  increases  in 
consequence  of  some  transformation.  It  is  not,  however,  in- 
dispensable that  the  temperature  of  the  system  be  raised, 
although  that  condition  is  generally  fulfilled,  and  it  tends  to 
increase  the  effects. 

The  initial  system  must,  however,  be  capable  of  existing 
by  itself,  at  least  for  some  little  period  of  time;  its  trans- 
formation taking  place  only  when  provoked  by  some  external 
cause,  such  as  friction,  ignition,  shock,  or  the  intervention  of 
a  chemical  agent,  either  causing  reactions  which  are  propa- 
gated chemically  (H2SO4  in  the  presence  of  a  mixture  of 
KC1O3  and  organic  substances),  or  causing  a  sharp  shock 


22  LECTURES   ON  EXPLOSIVES. 

which,  by  its  mechanical  effects,  leads  to  the  production  of 
the  explosive  wave  and  detonation  in  general. 

General  List  of  Explosives. — As  classified  by  Berthelot, 
the  various  explosives  are  divided  into  eight  distinct  groups, 
as  follows : 

First  Group. — Explosive  gases,  such  as — 

1.  Ozone,  hypochlorous  acid,  the  gaseous  oxides  of  chlo- 
rine, etc.,  which  detonate  under  very  slight  influences,  such  as 
slight  heating  or  sudden  compression. 

2.  Various    gases    formed   with    absorption    of  heat,  but 
more  stable ;  gases  which  detonate  neither  when  heated  pro- 
gressively   nor   when    moderately    compressed.     They    may, 
however,  be  detonated  by  the  action  of  fulminating  mercury. 
Such  are  acetylene,  nitrogen  dioxide,  cyanogen,  etc. 

Second  Group. — Detonating  gaseous  mixtures,  formed  by 
the  combination  of  oxygen  or  chlorine  with  hydrogen,  and 
gases  or  vapors  of  the  hydrocarbons. 

Third  Group. — Explosive  inorganic  compounds,  definite 
bodies,  liquid  or  solid,  susceptible  of  being  detonated  by 
shock,  friction,  or  heat;  such  as — 

1.  Nitrogen  sulphide,  nitrogen  chloride,  nitrogen  iodide, 
mercury  nitrate,  and  certain  other  metallic  nitrates ;  the  ful- 
minating oxides  of  gold  and  mercury. 

2.  The  liquid  oxyacids  of  chlorine  and  concentrated  per- 
manganic acid. 

3.  The  solid  salts  of  ammonium,  formed  by  the  oxyacids 
of  chlorine,  nitrogen,  chromium,  manganese,  and  others. 

Fourth  Group. — Explosive  organic  compounds,  definite 
bodies,  liquid  or  solid,  susceptible  of  being  detonated  by 
shock,  friction,  or  heat ;  such  as — 

1.  Nitric  ethers,  properly  so  called;  e.g.,  nitroglycerine. 

2.  Nitro-derivatives   of   the   carbohydrates;    e.g.,  cotton, 
paper,  wood,  and  other  various  kinds  of  cellulose. 

3.  Nitro-derivatives  of  the  aromatic  hydrocarbons ;    e.g., 
tri-nitro-phenol   and   its    derivatives,  nitro  -  oxyphenol,  tetra- 
nitro-methane,  chloro-nitro-methane,  etc. 

4.  Diazo-derivatives,  e.g.,  diazobenzene  nitrate  and  sim- 


THERMOCHEMISTRY  AND    CLASSIFICATION.  2$ 

ilar  bodies,  nitrolic  acids  and  other  poly-nitro-derivatives, 
nitro-ethane,  to  which  the  fulminates  of  mercury  and  silver, 
etc.,  seem  to  belong. 

5.  Derivatives  of  highly  oxygenated  mineral  acids,  such 
as,  on  the  one  hand,  nitrites,  nitrates,  chlorates,  perchlorates, 
chromates,  permanganates  of  organic  alkalies ;    on  the  other 
hand,  nitrous  ethers,  perchloric  ethers,  etc. 

6.  Explosive    derivatives    of    hydrogen    peroxide,    ethyl, 
acetyl,  etc.,  peroxides. 

7.  Hydrocarbon  derivatives  of  mineral  oxides  which  can 
be  easily  reduced,  especially  the  salts  of  silver  and  mercury 
oxides;    e.g.,  silver  oxalate,  mercury  oxycyanide,  etc. 

8.  Hydrocarbon  derivatives  and  other  bodies  characterized 
by  an  excess  of  energy  with  relation  to  their  elements,  such 
as  metallic  acetylides,  etc. 

Fifth  Group. — Mixtures  of  definite  explosive  compounds 
with  inert  substances. 

All  of  the  foregoing  explosives,  solid  or  liquid,  can  be 
mixed  with  inert  materials  in  order  to  moderate  their  action ; 
e.g.,  dynamite,  wet  guncotton,  camphorated  guncotton,  etc. 

Sixth  Group. — Mixtures  consisting  of  an  explosive  oxidiz- 
able  compound,  and  a  non-explosive  oxidizing  substance  which 
is  used  to  insure  the  complete  combustion  of  the  former,  such 


1.  Guncotton    mixed    with    potassium    and    ammonium 
nitrate,  potassium  picrate  mixed  with  potassium   chlorate  or 
nitrate,  etc. 

2.  Mixtures  of  nitric  acid  with  nitro-compounds;  e.g.,  di- 
nitro- benzene,  nitro-toluenes,  picric  acid,   etc.,  mixed  gener- 
ally in  the  form  of  paste. 

3.  Mixtures  of  nitric  peroxide  and  nitro-compounds. 
Seventh  Group. — Mixtures   with    an    explosive    oxidizing 

base. 

1.  Mixtures  consisting  of  an  explosive  containing  an  ex- 
cess of  O,  such  as  nitroglycerine,  and  an  oxidizable  substance, 
such  as  carbon  dynamite. 

2.  Gum  dynamite. 


24  LECTURES   ON  EXPLOSIVES. 

Eighth  Group. — Mixtures  consisting  of  oxidizable  and  ox- 
idizing substances,  solid  or  liquid,  neither  of  which  is  explo- 
sive separately.  Such  are — 

1.  Black  powder  formed  by  mixing  sulphur,  carbon,  and 
potassium  nitrate. 

2.  Powders  formed  by  mixing  hydrocarbon  compounds, 
charcoal,    coal,   wood,    sawdust,   various    kinds    of    cellulose, 
starch,  sugar,  or  by  mixing  sulphur  and  metals  with  metallic 
nitrates. 

3.  Liquid  or  pasty  mixtures  formed  by  mixing  liquid  ni- 
tric acid  either  with  a  combustible  liquid  or  with  a  solid  sub- 
stance on  which  it  does  not  act  instantaneously. 

4.  Mixtures  of  liquid  nitric  peroxide  with  various  oxidiz- 
able substances,  such  as  carbon  bisulphide,  petroleum  (refined), 
etc. 

5.  Mixtures  of  combustibles  and  chlorates  and  perchlo- 
rates. 

6.  Mixtures  of  combustibles  with  various  supporters    of 
combustion,    such    as    potassium    bichromate,    chromic    acid, 
oxides  of  copper,  lead,  antimony,  bismuth,  etc. 

7.  Mixtures  of   a  sulphide,    a  metallic   phosphide,    or  of 
analogous  binary  compounds  with  another  metal  capable  of 
displacing  the  former  in  gaseous  form  with  the  liberation   of 
heat. 

Explosive  Mixtures  and  Explosive  Compounds. — For 
practical  purposes  it  is  more  convenient  to  divide  explosives 
into  two  general  classes,  explosive  mixtures  and  explosive 
compounds,  according  to  the  manner  in  which  the  constituent 
elements  or  substances  are  associated.  These  two  classes 
may  be  further  subdivided  according  to  the  nature  and  action 
of  their  several  ingredients. 

Explosive  Mixtures. — The  first  class  consists  of  those 
explosive  substances  which  are  merely  intimate  mechanical 
mixtures  of  certain  ingredients,  and  which  can  be  again  sep- 
arated more  or  less  completely  by  mechanical  means}  not  in- 
volving chemical  action. 


. 


THERMOCHEMISTRY  AND    CLASSIFICATION.  2$ 

These  ingredients  do  not,  as  a  rule,  possess  explosive 
properties  in  their  separate  condition.  There  are  some,  how- 
ever, which  might  almost  be  classed  in  both  categories ;  for 
example,  picric  powder  is  composed  of  ammonium  picrate  and 
saltpetre,  the  former  of  which  contains  an  explosive  molecule,  > 
but  is  mixed  with  the  latter  to  supply  additional  oxygen  and 
thus  increase  the  force. 

If  a  substance  that  will  burn  freely  in  air,  combining  gradu- 
ally with  the  oxygen  of  the  atmosphere,  be  ignited  in  pure 
oxygen  gas,  the  combustion  will  be  much  more  rapid,  and  the 
amount  of  heat  generated  greater  than  at  the  ordinary  atmos- 
pheric pressure.  If  it  be  possible  to  burn  the  substance  in  a 
very  condensed  atmosphere  of  oxygen,  we  can  readily  imagine 
the  combustion  being  very  greatly  accelerated,  and  therefore 
increased  in  violence ;  this  is  what  is  ordinarily  effected  by  an 
explosive  "  mixture."  A  combustible  body  and  a  supporter 
of  combustion  are  brought  into  extremely  close  contact  with 
one  another  by  means  of  intimate  mechanical  mixture;  also, 
the  supporter  of  combustion,  or  oxidizing  agent,  is  present  in 
a  very  concentrated  form,  constituting  what  may  be  termed  a 
magazine  of  condensed  oxygen,  solid  or  liquid.  In  the  case 
of  the  explosion  of  a  definite  chemical  compound,  the  charge 
may  be  considered  as  the  resolution  of  a  complex  body  into 
simpler  forms;  this  is  not,  however,  always  the  case  where 
a  mechanical  mixture  is  concerned ;  gunpowder,  for  example, 
may  be  said  to  contain  two  elementary  substances,  C  and  S, 
not  in  chemical  union. 

Explosive  Compounds. — In  an  explosive  "  compound  " 
the  elements  are  all  in  chemical  combination,  presenting  a 
definite  explosive  "molecule,"  which  contains,  so  to  speak, 
both  the  combustible  and  the  supporter  of  combustion  in  the 
closest  possible  union ;  we  can  therefore  understand  its  action 
being  much  more  sudden  and  violent  than  that  of  the  most 
intimate  mechanical  mixture. 

For  purposes  of  instruction  these  two  principal  classes  will 
be  further  subdivided  as  follows: 


26  LECTURES   ON  EXPLOSIVES. 

Explosive  Substances. 

I.    Explosive  Mixtures. 

1.  Explosive  Mixtures  of  the  Nitrate  Class. 

2.  Explosive  Mixtures  of  the  Chlorate  Class. 
II.    Explosive  Compounds. 

1.  Nitro-substitution  Products. 

2.  Nitric  Ethers,  or  Esters. 

A.  Guncotton  and  its  Derivatives. 

B.  Nitroglycerine  and  its  Derivatives. 

a.  Dynamite  with  an  Inert  Base. 

b.  Dynamite  with  a  Combustible  Base. 

c.  Dynamite  with  an  Explosive  Base. 

a.   Base  is  an  Explosive  Mixture. 

a  .    Mixture  belongs  to   Ni- 
.    .  trate  Class. 

/3' '.    Mixture  belongs  to  Chlo- 
rate Class. 

ft.   Base  is  an  Explosive  Compound. 
a' .   Compound     is    a    Nitro- 
substitution  Product. 
/?'.   Compound    is    a    Nitric 
Ester. 

3.  Explosives  of  the  Sprengel  Class. 

4.  Fulminates,  Amides,  and  Similar  Compounds. 

5.  Smokeless  Powders. 

Although  the  lines  of  division  between  the  various  classes 
as  given  above  are  not  clearly  drawn,  and  one  or  more  explo- 
sives in  one  class  may  appear,  on  account  of  the  nature  of 
their  composition  or  action,  to  fall  under  another  class,  or 
perhaps  to  partake  of  the  characteristics  of  two  or  more  classes, 
this  classification  is  especially  well  adapted  for  practical  in- 
struction in  the  laboratory. 

The  Composition  of  Explosives. — Any  substance  con- 
taining in  itself  the  necessary  elements  to  produce  combustion 
may  under  certain  conditions  give  rise  to  an  explosion  of  a 
very  low  order.  The  prime  essentials,  therefore,  of  every 


THERMOCHEMISTRY  AND    CLASSIFICATION.  2f 

explosive,  with  very  few  exceptions  which  will  be  treated  sep- 
arately, are  a  combustible  and  a  supporter  of  combustion. 
The  nature  of  the  products  of  explosion  differ  from  the  phe- 
nomena attending  ordinary  combustion  principally  on  account 
of  the  rapidity  with  which  the  reaction  is  propagated,  but,  as 
already  stated,  the  characteristic  products  of  an  explosive  reac- 
tion are  gas  and  heat ;  therefore  those  substances  which,  while 
undergoing  decomposition  and  recombination,  give  rise  to  the 
greatest  volume  of  gas  and  the  maximum  quantity  of  heat  are 
best  adapted  to  enter  into  the  composition  of  an  explosive. 
Oxygen  has  long  been  regarded  as  the  most  energetic  sup- 
porter of  combustion,  but  for  obvious  reasons  is  of  practical 
application  only  in  combination  with  other  elements.  The 
various  oxidizable  substances  used  in  explosive  agents  contain 
generally  carbon,  hydrogen,  nitrogen,  sulphur,  etc.,  while  the 
oxidizers  appear  in  the  form  of  the  various  nitrates,  chromates, 
chlorates,  etc.,  in  which  the  oxygen  is  held  more  or  less  closely 
in  union  with  other  elements. 

When  explosion  takes  place  the  nitrogen  parts  with  its 
oxygen  to  the  carbon,  for  which  it  has  a  great  affinity,  form- 
ing carbonic  acid  (CO2)  and  carbonic  oxide  (CO)  gases,  the 
combination  being  accompanied  with  great  generation  of  heat, 
and  the  nitrogen  gas  is  set  free.  In  most  explosives  there  is  also 
hydrogen  accompanying  the  carbon,  and  by  its  combustion 
producing  an  extremely  high  temperature;  it  also  combines 
with  part  of  the  oxygen  to  form  water  in  the  form  of  greatly 
expanded  vapor. 

The  chief  explosive  compounds  are  formed  from  some  or- 
ganic substance  containing  carbon,  hydrogen,  and  oxygen,  by 
introducing  into  it,  through  the  action  of  concentrated  nitric 
acid,  a  certain  portion  of  nitric  peroxide  (NOa),  in  substitution 
for  an  equivalent  amount  of  hydrogen.  A  new  compound 
differing  outwardly  very  little,  if  at  all,  from  the  original  sub- 
stance is  thus  formed,  but  in  a  very  unstable  state  of  chemi- 
cal equilibrium,  because  of  the  feeble  union  of  the  nitrogen 
and  oxygen  in  the  NO,  molecule.  A  slight  disturbing  cause 
brings  into  play  the  stronger  affinity  of  the  carbon  and  hydro- 


28  LECTURES   ON  EXPLOSIVES. 

gen  for  the  large  store  of  oxygen  contained  in  the  new  com- 
pound. 

It  is  not,  however,  necessary  that  a  substance  should  contain 
the  necessary  elements  to  produce  combustion  in  order  to  be 
an  explosive.  Thus  the  two  very  unstable  and  practically 
useless  explosive  substances,  the  chloride  and  iodide  of  nitro- 
gen, contain  neither  carbon  nor  oxygen ;  but  their  great  vio- 
lence is  equally  caused  by  the  feeble  affinity  of  nitrogen  for 
other  elements,  large  volumes  of  gaseous  matter  being  sud- 
denly disengaged  from  a  very  small  quantity  of  a  liquid  and 
solid  body  respectively.  An  additional  and  more  satisfactory 
explanation  of  the  explosive  force  of  these  and  similarly  con- 
stituted compounds  is  to  be  found  in  the  principles  of  thermo- 
chemistry already  alluded  to. 


LECTURE   III. 

INGREDIENTS  ENTERING  INTO  THE  COMPOSITION  OF  EX- 
PLOSIVES, AND  SUBSTANCES  USED  IN  THEIR  PREPA- 
RATION. 

I,  Potassium  Nitrate  (Saltpetre  or  Nitre,  KNO3)  is 
found  in  some  parts  of  India,  especially  in  Bengal  and  Oude, 
where  it  sometimes  appears  as  a  white  incrustation  on  the  sur- 
face of  the  soil,  and  is  often  mixed  with  it  to  a  considerable 
depth.  The  nitre  is  extracted  from  the  earth  by  treating  it 
with  water,  and  the  solution  is  evaporated,  at  first  by  the 
heat  of  the  sun  and  afterwards  by  artificial  heat,  when  the 
impure  crystals  are  obtained,  which  are  packed  in  bags  and 
sent  to  different  countries  as  groiigh  (or  impure  saltpetre).  It 
contains  a  quantity  of  extraneous  matter  varying  from  I  to 
10  per  cent,  and  consisting  of  the  chlorides  of  potassium 
and  sodium,  sulphates  of  potash,  soda,  and  lime,  vegetable 
matter  from  the  soil,  sand  and  moisture.  The  number  repre- 
senting the  weight  of  impurity  present  is  usually  termed  the 
refraction  of  the  nitre,  in  allusion  to  the  old  method  of  esti- 
mating it  by  casting  the  melted  nitre  into  a  cake  and  examin- 
ing its  fracture,  the  appearance  of  which  varies  according  to 
the  amount  of  foreign  matter  present. 

Saltpetre  also  occurs  as  a  saline  crust  in  caverns  in  some 
parts  of  the  globe ;  and  in  the  vicinity  of  Monclova,  Mexico, 
it  is  found  in  great  purity  in  veins  or  mines. 

It  exists  in  certain  plants,  and  is  formed  spontaneously  by 
the  decomposition  of  animal  and  vegetable  substances  when 
mixed  with  substances  containing  potash  and  .kept  at  an  even 

29 


30  LECTURES   ON  EXPLOSIVES. 

temperature  in  moist  situations.  On  this  principle  artificial 
nitre-beds  are  made,  from  which  large  quantities  of  nitre  are 
obtained,  in  France,  Germany,  Sweden,  and  Hungary.  These 
beds  consist  of  accumulations  of  vegetable  and  animal  refuse,  to 
which  are  added  old  mortar,  limestone,  ashes,  etc.  From  time 
to  time  stable-drainings  are  poured  over  the  mass,  in  which,  at 
an  atmospheric  temperature  of  from  60°  to  70°  F.,  the  nitrates 
of  the  various  metals  are  formed.  These  nitrates,  removed 
from  time  to  time,  and  extracted  by  means  of  water,  consist 
principally  of  the  salts  of  potassium,  calcium,  magnesium, 
and  ammonium,  the  last  three  of  which  may  be  converted 
into  potassium  nitrate  by  decomposing  them  with  potassium 
carbonate.  The  nitrified  earth  of  India  yields  about  one 
fifth  of  its  weight  of  nitre ;  that  of  the  nitre  caves  from  one 
to  ten  pounds  of  nitre  to  the  bushel ;  while  the  best  nitre- 
beds  afford  annually  about  a  quarter  of  a  pound  of  nitre  to  a 
bushel  of  earth. 

Most  of  the  saltpetre  used  in  the  United  States  for  the 
manufacture  of  gunpowder  is  obtained  from  India,  whence  it 
is  imported  in  a  crystallized  state  called  crude  saltpetre,  con- 
taining generally  from  15  to  18  per  cent  of  foreign  salts, 
earths,  and  water.  The  method  of  purifying  it  for  use  in  the 
manufacture  of  gunpowder  will  be  described  hereafter. 

Potassium  nitrate  is  distinguishable  by  the  long  striated  or 
grooved  six-sided  prismatic  form  in  which  it  crystallizes,  and 
by  the  deflagration  which  it  produces  when  thrown  on  red- 
hot  coals.  It  fuses  at  about  635°  F.  to  a  colorless  liquid, 
which  solidifies  on  cooling  to  a  translucent,  brittle,  crystal- 
line mass.  At  red  heat  it  effervesces  from  the  escape  of 
bubbles  of  oxygen,  and  is  converted  into  potassium  nitrite 
(KNO2),  which  is  itself  decomposed  by  a  higher  temperature, 
evolving  nitrogen  and  oxygen,  and  leaving  a  mixture  of  potas- 
sium oxide  (K2O)  and  potassium  peroxide  (K2O2).  In  con- 
tact with  any  combustible  body  it  undergoes  decomposition 
with  great  rapidity,  five  sixths  of  the  oxygen  being  available 
for  the  oxidation  of  the  combustible  substance  and  the  nitro- 
gen being  evolved  in  a  free  state. 


INGREDIENTS   OF  EXPLOSIVES.  31 

2.  Sodium  Nitrate  (Cubical  or  Chili  Saltpetre,  NaNO3). 
This  salt  has  been  proposed  as  a  substitute  for  potassium 
nitrate  in  the  manufacture  of  gunpowder,  but,  on  account  of 
its  hygroscopic  properties,  it  has  never  been  adopted,  since 
gunpowder  made  with  it  would,  under  ordinary  conditions, 
soon  become  useless  from  moisture  absorbed  from  the  atmos 
phere.  In  a  hot,  dry  climate  sodium  nitrate  powders,  if 
made  only  a  short  time  before  being  required  for  use,  would 
be  valuable,  and  cheaper  than  ordinary  gunpowder,  and  such 
powders  were  largely  used  in  the  construction  of  the  Suez 
Canal,  and  continue  to  be  used  for  blasting  in  mines.  Abso- 
lutely pure  sodium  nitrate  is  said  to  be  not  unduly  deliques- 
cent, but  the  material  as  found  in  commerce  contains  other 
salts  which  are  supposed  to  induce  this  property,  and  are 
difficult  to  remove  by  any  reasonably  economical  process. 

The  salt  is,  however,  indirectly  largely  and  increasingly 
used  in  the  manufacture  of  gunpowder,  for  by  the  simple  proc- 
ess of  boiling  it  with  potassium  chloride  it  is  converted  into 
KNO3,  which  is  retained  in  the  hot  solution  while  sodium 
chloride  is  deposited — 

NaN03  +  KC1  =  KNO3  +  NaCl. 

Practically  the  method  adopted  is  to  add  the  potassium 
chloride  (now  obtained  largely  from  the  refuse  of  beet-root 
used  in  sugar-manufacture)  to  a  boiling  solution  of  sodium 
nitrate,  removing  the  sodium  chloride  formed  by  means  of  a 
perforated  ladle,  and  allowing  the  suspended  impurities  to 
settle.  The  supernatant  liquid  is  then  run  into  crystallizing 
pans,  and  the  potassium  nitrate  is  deposited. 

As  an  oxidizing  agent  sodium  nitrate  contains  more  avail- 
able oxygen  than  the  potassium  salt,  but  at  very  high  tem- 
peratures it  exercises  a  less  powerful  oxidizing  action  upon 
combustible  bodies. 

Sodium  nitrate,  as  its  commercial  name,  Chili  saltpetre, 
indicates,  is  found  in  vast  quantities  in  Chili  (especially  in  the 
districts  of  Tarapaca  and  Atacama),  where  in  its  crude  state  it 
is  known  as  caliche.  The  crude  salt  contains  as  impurities 


32  LECTURES   ON  EXPLOSIVES. 

sodium  chloride  and  various  other  salts,  sand,  clay,  etc.  On 
account  of  the  form  in  which  it  crystallizes,  rhombohedra,  this 
salt  is  also  called  ciibical  saltpetre. 

3.  Ammonium  Nitrate. — Ammonium  nitrate  is  very  spar- 
ingly found  in  nature,  but  is  readily  prepared  artificially.      In 
small  quantities  it  can  be  made  by  neutralizing  nitric  acid  with 
ammonium  carbonate  and  evaporating  the  solution   until  the 
surface  of  the  solution  is  covered  with  a  thin  crystalline  layer 
of  the  salt,  and  then  allowing  the  bulk  of  the  nitrate  to  crys- 
tallize out,  which  it  does  in  the  form  of  large  columnar  crys- 
tals, not  unlike  those  of  potassium  nitrate,  having  a  bitter 
saline  taste. 

A  method  has  been  patented  (Benker)  involving  the  double 
decomposition  of  sodium  nitrate  and  ammonium  sulphate. 
These  salts  are  dissolved,  and  a  mixture  of  the  two  solutions 
is  submitted  to  a  temperature  (—15°  C.)  at  which  the  ammo- 
nium nitrate  will  freeze  and  separate  out,  while  the  sodium 
sulphate  remains  in  solution. 

Commercially,  however,  it  is  prepared  by  causing  ammo- 
nium sulphate  and  lime  to  react  with  the  aid  of  heat,  and 
absorbing  the  ammonia  gas  thus  liberated  in  dilute  nitric  acid. 

Like  all  ammonium  salts,  the  nitrate,  when  heated  (espe- 
cially if  previously  moistened  with  potassium  or  sodium 
hydrate),  evolves  ammonia  gas  and  becomes  acid.  It  melts 
at  100°  C.,  and  is  completely  decomposed  at  200°  C.,  with 
the  formation  of  N2O.  Ammonium  nitrate  is  highly  hygro- 
scopic, rapidly  becoming  liquefied  upon  exposure  to  the 
atmosphere.  When  dissolved  in  water,  the  act  of  solution  is 
attended  with  considerable  absorption  of  heat,  and  this  prop- 
erty is  utilized  in  many  so-called  freezing-mixtures. 

Ammonium  nitrate  has  recently  attracted  considerable 
attention  as  one  of  the  substances  investigated  with  the  object 
of  obtaining  a  base  for  one  class  of  smokeless  powders.  But 
on  account  of  its  great  hygroscopicity  it  has  been  practically 
abandoned  as  an  ingredient  for  military  powders. 

4.  Barium,  Lead,  and  Strontium  Nitrates  (Ba(NO3)2, 
Pb(NO3)2,   Sr(NO3)3).— These  salts  have  been   experimented 


INGREDIENTS   OF  EXPLOSIVES.  33 

with  as  oxidizers  in  various  powders,  but,  with  the  exception 
of  barium  nitrate  powder,  none  of  them  have  ever  attained  a 
commercial  value,  and  that  one  has  almost  entirely  disap- 
peared except  as  a  relic  of  the  past. 

Barium  Nitrate  has  been  substituted  principally  to  pro- 
duce a  slower-burning  powder,  but  the  increased  weight  of 
the  powder  resulting  from  such  a  substitution  is  a  serious 
objection.  For  instance,  the  chemical  equivalent  of  KNO3 
being  101,  and  that  of  Ba(NO,)a  130.5,  the  latter  salt  increases 
by  one  third  the  weight  of  the  oxidizing  agent  necessary  to 
consume  a  given  weight  of  the  combustible.  The  salt  is 
prepared  by  dissolving  the  native  carbonate  in  nitric  acid,  fil- 
tering the  solution,  and  evaporating.  It  crystallizes  in  trans- 
parent, colorless  octahedrons,  which  are  anhydrous.  They 
require  for  solution  8  parts  of  cold  and  3  parts  of  boiling 
water. 

Lead  Nitrate  is  prepared  by  dissolving  finely  ground 
litharge  (lead  carbonate)  in  dilute  nitric  acid,  allowing  the 
solution  to  settle,  and  decanting  the  clear  supernatant  liquid,, 
from  which  the  nitrate  crystallizes  out  in  white  octahedra.  It 
is  only  slightly  hygroscopic,  readily  decomposed  by  heat,  and 
for  its  chemical  equivalent  (165.5)  yields  for  equal  equivalents 
one  fifth  more  oxygen  than  the  other  nitrates.  The  objec- 
tions against  its  use  in  explosives  are  first  its  cost;  secondly, 
the  ease  with  which  it  decomposes  (with  reduction  of  lead  to 
the  metallic  state),  and  the  gases  developed  upon  decompo- 
sition, which  are  very  deleterious.  It  is  therefore  used  only 
for  very  special  purposes. 

Strontium  Nitrate  demands  merely  passing  mention,  its 
use  being  entirely  limited  to  pyrotechny  to  produce  a  brilliant 
red  flame. 

General  Qualitative  Tests  applicable  to  all  Nitrates.  —  I. 
All  nitrates  when  heated  upon  charcoal  by  means  of  the  blow- 
pipe deflagrate  with  considerable  violence. 

2.  Dissolve  a  crystal  of  ferrous  sulphate  in  a  solution  of  a 
nitrate.  Upon  adding  carefully  a  few  drops  of  concentrated 
sulphuric  acid  down  the  side  of  a  test-tube  containing  the 


34  LECTURES  ON  EXPLOSIVES. 

double  solution,  a  reddish-brown  or  purple  layer  will  be 
formed  at  the  junction  of  the  two  liquids.  (Sometimes  the 
layer  is  black,  due  to  the  formation  of  an  unstable  compound 
having  the  composition  2FeSO4.NO.) 

3.  Introduce  into  a  test-tube  containing  a  nitrate  solution 
a  few  copper  turnings  and  a  few  drops  of  concentrated  sul- 
phuric  acid.      Upon  the  application   of   heat,    dark  reddish- 
brown  fumes  of  nitrogen  peroxide  (NaO4)  are  evolved,  which 
redden  but  do  not  bleach  litmus-paper. 

4.  To  a  solution  of  indigo   add  a  nitrate  solution.      No 
effect  is  noticed  until  heat  is  applied,  when  the  indigo  will  be 
bleached. 

5.  Boil    a   minute  quantity  of  gold-leaf    in   hydrochloric 
acid.      Upon   the  addition   of  a  small   quantity  of  a  nitrate 
solution   the  gold    disappears,  to  appear  again  as    a  purple 
precipitate  (purple  of  Cassius)  upon  the  addition  of  the  proto- 
chloride  of  tin  (solution). 

To  detect  the  presence  of  a  nitrate  in  a  suspected  solid, 
place  a  minute  quantity  upon  a  porcelain  surface,  moisten  it 
with  concentrated  sulphuric  acid,  and  introduce  a  minute  crys- 
tal of  brucine.  If  a  nitrate  be  present,  a  brilliant-scarlet  color 
will  appear. 

7.  To  apply  this   test  (6)  to  a  solution,  introduce  into  a 
a  test-tube  containing  the  suspected  nitrate  a  few  drops  of 
brucine  (i   part  of  brucine  to  300  parts  of  5$  dilute  sulphu- 
ric acid).     Upon  pouring  carefully  down  the  side  of  the  test- 
tube   a   few   drops  of  concentrated  sulphuric  acid,   a  bright- 
scarlet  layer  changing  to  yellow  will  appear  at  the  line  of  con- 
tact if  a  nitrate  be  present. 

8.  Another  delicate  test  applicable  to  suspected  solids  is 
as   follows  :     Place  a  minute  quantity  of  the  substance  sup- 
posed   to  contain    a    nitrate    upon    a    porcelain    surface    and 
moisten  it  with  a  drop  of  concentrated  sulphuric  acid.      Intro- 
duce  a  small  quantity  of   diphenylamine.       If  a  nitrate    be 
present,  a  deep-indigo  color  will  quickly  appear. 

9.  This  test  may  be  applied   to   a  solution  supposed  to 
contain  nitrate  as  follows  :    Introduce   into   a  test-tube  con- 


INGREDIENTS   OF  EXPLOSIVES.  35 

taining  the  solution  a  few  drops  of  diphenylamine  (dissolved 
in  sulphuric  acid),  and  then  pour  carefully  down  the  side  of 
the  test-tube.  If  a  nitrate  be  present  in  the  solution,  a  deep- 
indigo-colored  layer  will  appear  along  the  surface  of  con- 
tact. 

10.  The  presence  of  a  nitrate  in  solution  may  also  be 
detected  by  introducing  into  the  test-tube  a  few  crystals  of 
pyrogallic  acid,  and  then  pouring  a  few  drops  of  concentrated 
sulphuric  acid  down  the  side  of  the  tube.  The  presence  of  a 
nitrate  is  shown  by  the  appearance  of  a  deep-brown  color 
along  the  surface  of  contact. 

Tests  (6),  (7),  (8),  (9),  and(io)  are  extremely  delicate,  and 
since  sulphuric  acid  may  contain  traces  of  nitric  acid  (hydric 
nitrate),  it  is  necessary  to  test  the  sulphuric  acid  alone  in 
order  to  determine  its  purity  before  using  it  in  these  tests. 

To  determine  the  base  to  which  a  nitrate  belongs,  it  is 
generally  sufficient  to  apply  the  test  of  flame-coloration. 
Thoroughly  clean  a  loop  of  platinum  wire  (by  moistening  it 
with  strong  HC1  and  heating  it  intensely  until  no  color  is 
produced  in  a  non-luminous  Bunsen  flame),  dip  it  into  a  solu- 
tion of  the  nitrate,  and  introduce  the  loop  into  the  Bunsen 
flame  again : 

1.  If  the  color  imparted  to  the  flame  be  pale  lilac  as  seen 
directly,   but  changes  to  crimson  when  viewed    through    an 
indigo  prism,  the  base  is  potassium. 

2.  If  the  flame  seen  directly  be  intense  yellow,  but  fades 
away  or  appears  nearly  white  when  viewed  through  an  indigo 
prism,  the  base  is  sodium. 

3.  The   presence  of  both  potassium  and  sodium   in    the 
same  substance  may  be  detected  in  this  way,  since  the  intense 
yellow  will  obscure   the  faint  lilac  when  viewed  directly,  but 
the  crimson  color  due  to  the  presence  of  potassium  will  pre- 
dominate when  the  prism  is  applied. 

4.  The  coloration  produced  directly  by  the  barium  salt  is 
yellowish  green. 

5.  The  coloration  due  to  strontium  is  deep  crimson,  both 
directly  and  through  the  indigo  prism. 


36  LECTURES   ON  EXPLOSIVES. 

6.  The  presence  of  ammonium  is  readily  detected  by  the 
evolution  of  the  ammonia  gas  (detected  by  its  odor),  as  already 
indicated. 

7.  The  lead  salt  is  equally  easily  determined  by  the  reduc- 
tion of  lead  to  the  metallic  state  upon  charcoal  before    the 
blowpipe. 

Although  the  flame-colorations  will,  as  a  general  rule,  suf- 
fice to  determine  the  base,  a  more  satisfactory  though  tedi- 
ous test  is  that  of  the  spectroscope,  which  develops  the 
characteristic  spectra  of  each  of  the  several  elements. 

QUANTITATIVE  TESTS  FOR  NITRE. — As  has  been  already 
stated,  the  principal  impurities  contained  in  nitre  are  moist- 
ure, sand,  and  organic  matter,  potassium  and  sodium  chlorides, 
potassium,  sodium,  and  calcium  sulphates,  and  in  that  prepared 
from  NaNO3  a  little  of  the  latter  generally  remains.  These 
impurities  are  estimated  as  follows: 

Moisture. — The  moisture  is  determined  by  weighing  5 
gm.  in  a  watch-crystal  or  porcelain  crucible  (of  known  weight), 
and  placing  the  crystal  or  crucible  in  a  steam-oven  for  twenty- 
four  hours.  It  is  then  removed  from  the  oven,  allowed  to 
cool  under  a  desiccator,  and  reweighed.  The  loss  of  weight 
is  due  to  the  moisture  which  has  been  driven  off.  If  calcium 
or  magnesia  nitrates  are  present,  one  gramme  of  potassium 
chromate  (neutral)  is  added  to  prevent  their  decomposition. 

Insoluble  Matter. — Treat  with  water  the  mass  from  which 
the  mixture  has  been  eliminated  and  filter.  The  differ- 
ence in  weight  of  the  filter  before  and  after  (when  dry  and 
cool )  filtration  measures  the  insoluble  matter.  Concentrate 
the  filtrate  obtained  in  this  manner  by  evaporating  to  any 
volume  N.  Reserve  one  third  of  this  solution  for  the  esti- 
mation of  the  chlorides,  one  third  for  the  sulphates,  and  one 
third  for  calcium  salts.  Say  that  the  concentrated  solution 
measures  150  c.c. 

Chlorides. — Fifty  c.c.  are  placed  in  a  clean  porcelain 
dish,  about  30  milligrammes  of  pure  potassium  chromate  are 
added,  and  the  solution  is  stirred  until  the  salt  is  dissolved, 
coloring  the  solution  distinctly  yellow.  A  centinormal  solu- 


INGREDIENTS   OF  EXPLOSIVES.  37 

tion  of  silver  nitrate  is  prepared  by  dissolving  1.7  gm.  of  the 
salt  in  one  litre  (1000  c.c.)  of  distilled  water.  Each  cubic 
centimetre  of  this  solution  will  detect  0.000585  gm.  of  NaCl. 

AgN03  +  NaCl  =  AgCl  +  NaNO3. 

This  solution  is  carefully  added  from  a  burette  or  pipette, 
graduated  to  TV  c.c.,  the  solution  being  constantly  stirred 
until  the  red  color  just  begins  to  be  permanent.  The  amount 
of  silver  nitrate  solution  required  is  noted.  If  either  the 
solution  of  nitre  or  the  silver  solution  be  acid,  it  must  first 
be  neutralized  with  caustic  potash.  Suppose  2.6  c.c.  of  the 
centinormal  silver  solution  be  required ;  then  the  weight  of 
NaCl  in  the  nitre  is  found  as  follows: 

2.6  X  3  X  0.000585  =  0.004563  gm. ; 

whence  the  percentage  is  calculated  by  multiplying  the  latter 
number  by  20;  thus: 

0.004563  X  20  =  0.09126$  NaCl. 

Sulphates. — The  sulphates  are  estimated  by  means  of  a 
centinormal  solution  of  barium  chloride,  prepared  by  dis- 
solving 2.44  gm.  of  the  crystallized  salt,  BaCl2.2H2O,  in  one 
litre  (1000  c.c.)  of  distilled  water.  Each  c.c.  of  this  solu- 
tion will  detect  0.00174  gm.  K2SO4 ,  or  0.00142  gm.  Na2SO4. 

K2SO4  +  BaCl2  =  2KC1  +  BaSO4. 
Na2S04  +  BaCl2  =  2NaCl  +  BaSO4. 

Five  c.c.  of  the  solution  TV"  are  put  into  a  test-tube,  and  the 

N 

BaCl2.2H2O  is  carefully  added  by  means  of  a  pipette  or 

100 

burette,  the  amount  thus  added  being  carefully  noted,  and 
the  precipitate  thus  formed  allowed  to  settle.  As  soon  as 

N 
the  precipitate  has  entirely  subsided,  a  little  more  of  the 

solution  is  added,  and  this  process  is  continued  until  upon  the 


38  LECTURES   ON  EXPLOSIVES. 

addition  of  more  of  the  reagent  no  further  precipitate  ap- 
pears. Having  thus  approximately  determined  the  amount  of 

N 
-  BaCla.2HaO  required  to  precipitate,  the  operation  is  then 

continued  as  indicated  in  the  determination  of  sulphur  in 
gunpowder,  and  the  exact  amount  determined.  Knowing 
the  number  of  c.c.  required  to  precipitate  all  of  the  sul- 
phates, the  weight  and  percentage  of  the  latter  are  calculated 
as  in  the  case  of  the  chlorides. 

Calcium  Salts.  —  The  calcium  salts  are  estimated  by 
means  of  a  centinormal  solution  of  ammonium  oxalate,  pre- 
pared by  dissolving  160  grammes  of  the  crystallized  salt, 
Ca(NH4)3O4.2H3O,  in  I  litre  of  water.  Each  c.c.  of  this 
solution  will  detect  0.00164  gm.  Ca(NO3)2. 

Ca(NO,)s  +  (NHJA-CA  =  2(NH4)NO.  +  CaO.C.0.- 
The  operation  in  this  case  is  similar  in  every  particular  to 
that  used  in  case  of  the  sulphates,  and  the  final   calculations 
are  similar  to  those  adopted  in  case  of  the  chlorides  and  sul- 
phates. 

5.  Potassium  Chlorate  (KC1O3). — This  salt,  so  interest- 
ing in  its  application  to  the  manufacture  of  explosives,  is  made 
commercially  by  mixing  potassium  carbonate  and  lime  in  the 
proportions  of  I  to  6,  and  saturating  the  damp  mixture  with 
chlorine.  On  treating  the  mass  with  boiling  water  a  solution 
is  obtained  which  contains  potassium  chlorate  and  calcium 
chloride ;  the  latter  being  very  soluble  remains  in  the  solution, 
while  the  KC1O,  crystallizes  out  upon  cooling.  The  reaction 
may  be  represented  as  follows: 

KaC03  +  6CaO  +  Cllf  =  2KC1O3  +  5CaCl2+  CaCO3. 

Potassium  chlorate  is  soluble  in  about  twenty  parts  of  cold 
and  two  parts  of  boiling  water;  the  crystals  are  anhydrous, 
flat,  and  tabular;  in  taste  it  somewhat  resembles  saltpetre. 
Like  the  nitrate,  KC1O3  is  employed  as  an  oxidizing  agent. 
When  heated  it  gives  off  the  whole  of  its  oxygen  and  leaves 
potassium  chloride.  It  deflagrates  violently  with  combustible 


INGREDIENTS  OF  EXPLOSIVES.  39 

matter,  explosion  resulting  from  friction  or  blows,  its  extreme 
sensitiveness  in  this  respect  precluding  its  use  in  the  manufac- 
ture of  gunpowder,  although  it  is  used  extensively  in  pyro- 
techny.  The  decomposition  of  KC1O3  by  heat  into  oxygen 
and  potassium  chloride  is  attended  with  evolution  of  heat,  one 
part  of  the  salt  producing  39  cal.,  which,  according  to  the 
principles  of  thermochemistry,  explains  the  unusual  energy 
developed  by  explosives  in  which  this  salt  enters  as  an  ingre- 
dient. 

Qualitative  Tests  for  Chlorates.  —  I.  Like  the  nitrates,  the 
chlorates  are  soluble,  and  deflagrate  when  heated  on  charcoal 
by  means  of  the  blowpipe. 

2.  Introduce  into  a  test-tube  a  few  small  crystals  of  the 
salt,  and  pour  upon  them  a  few  drops  of  concentrated  sulphuric 
acid.      If  a  chlorate  be  present,  a  brown  coloration  will  result, 
and  upon  heating  gently  an  explosion  will  ensue,  with  the  pro- 
duction of  crackling  sounds. 

(N.  B. — Only  very  minute  quantities  of  the  salt  should  be 
used,  and  the  mouth  of  the  test-tube  should  be  turned  away 
from  the  person  while  making  this  experiment.) 

During  this  decomposition  a  greenish-yellow  gas,  chloric 
peroxide  (C12O4),  is  evolved,  which  is  readily  recognized  by  its 
suffocating  odor. 

3.  If  a  cold  dilute  solution  of  indigo  is  gradually  added  to 
a  cold  solution  of  KC1O3  so  as  to  color  the  solution  faintly  but 
distinctly  blue,  and  a  few  drops  of  concentrated  sulphuric  acid 
be  added  and  the  mixture  be  agitated,  the  color  will  disappear. 

4.  A  more   delicate   test,  depending   upon   the  action   of 
chlorine  upon  indigo  (bleaching),  may  be  applied  as  follows : 
Dissolve  a  little  of  the  salt  in  water,  and   color  the  solution 
with  a  few  drops  of  indigo  dissolved  in  sulphuric  acid.      Add 
next  a  little  diluted  H2SO4,  and  then  drop  by  drop  a  solution 
of  sodium  sulphite.      Immediately  the  blue  color  will  disap- 
pear due  to  the  action  of  the  liberated  chlorine,  the  sulphur- 
ous acid  depriving  the  chloric  acid  of  its  oxygen. 

5.  In  testing  an  explosive  which  is  supposed  to  contain  a 
mixture  of  chlorates  and  nitrates,  dissolve  a  small  quantity  in 


40  LECTURES   ON  EXPLOSIVES. 

warm  water  and  filter.  The  filtrate  will  contain  the  nitrates 
and  chlorates.  Introduce  a  little  of  the  filtrate  into  a  test- 
tube,  add  to  it  a  few  drops  of  sulphuric  acid,  and  a  small  strip 
of  zinc.  Heat  gently,  and  add  a  few  drops  of  silver  nitrate. 
If  a  chlorate  be  present  a  white  precipitate  of  silver  chloride 
will  be  thrown  down. 

6.  Nitric  Acid  (Hydric  Nitrate,  HNO3).  —  Nitric  acid  is 
prepared  on  a  small  scale  by  distilling  potassium  nitrate  with 
an  equal  weight  of  concentrated  sulphuric  aid.  When  pre- 
pared in  large  quantities,  sodium  nitrate,  which  is  cheaper  and 
furnishes  a  larger  proportion  of  nitric  acid,  is  substituted  for 
the  potassium  salt. 

Either  of  two  reactions  may  occur: 

NaN03+H2S04  =  HNO3  +  NaHSO4; 
2NaNO,  +  H2SO4  =  2HNO3  +  Na2SO4. 

For  practical  reasons  the  first  equation  represents  the 
relative  proportions  in  which  the  ingredients  are  used.  The 
sodium  nitrate  is  introduced  into  an  iron  cylinder  lined  with 
fire-clay  to  protect  it  from  the  action  of  the  acid,  and  equal 
weight  of  H2SO4  is  poured  on  it.  The  furnace  in  which  these 
cylinders  are  built  (generally  in  pairs)  is  then  fired  up,  the 
nitric  acid  passes  off  in  vapor,  is  condensed,  and  received  in 
stoneware  jars. 

Thus  obtained,  nitric  acid  has  a  specific  gravity  of  from 
1.50  to  1.52,  and  has  a  color  varying  from  straw-yellow  to 
reddish  yellow,  due  to  the  presence  of  hyponitric  acid,  al- 
though it  may  be  entirely  bleached,  so  as  to  appear  perfectly 
colorless.  Upon  exposure  to  sunlight  it  is  partially  decom- 
posed, with  the  formation  of  hyponitric  acid  and  water.  It 
is  extremely  corrosive,  staining  the  skin  deep  yellow  and 
causing  total  disorganization.  The  facility  with  which  nitric 
acid  parts  with  a  portion  of  its  oxygen  renders  it  very  valu- 
able as  an  oxidizing  agent,  and  it  is  to  this  property  that  it 
owes  its  importance  in  its  relations  to  explosives.  Compara- 
tively few  substances  which  are  capable  of  forming  com- 
pounds with  oxygen  can  escape  oxidation  when  treated  with 


INGREDIENTS   OF  EXPLOSIVES.  41 

HNO3.  Its  action  upon  organic  substances  is  most  marked, 
and  in  many  cases  the  resulting  products  exhibit  a  most 
interesting  relation  to  original  substances. 

The  principal  use  for. nitric  acid  is  the  manufacture  of  the 
various  nitro-compounds,  and  the  nature  of  its  action  will  be 
shown  later  in  connection  with  nitro-substitution  products  as 
a  distinct  class  of  explosives. 

Tests  for  Nitric  Acid. — Considered  as  a  true  nitrate — 
hydric  nitrate — the  several  tests  enumerated  for  the  nitrates 
apply  equally  in  the  case  of  nitric  acid. 

Other  special  tests  to  determine  the  quality  of  the  acid 
are,  however,  of  great  value. 

1.  The  acid  should  be  clear,  and  the  color  should  not  be 
a  deeper  yellow  than  that  of  a  solution  of  pure  picric  acid 
in  water. 

2.  Determine  its  real  specific   gravity  by  weighing  in  a 
carefully    calibrated    specific  -  gravity   bottle    at    15°   C.,   and 
comparing  the  weight  obtained  with  the  weight  of  the  same 
volume  of  pure  distilled  water  at  the  same  temperature.      It 
should  not  be  less  than  1.50  at  15°  C. 

3.  Ten  drops  evaporated  upon  a  piece  of  clean  platinum- 
foil   should   leave   no    residue   indicative   of   the   presence   of 
metals. 

4.  About  2  c.c.  of  the  acid  diluted  and  put  in  a  test-tube 
should  exhibit  no  turbidity  upon  the  addition  of  a  few  drops 

N 
of  --  HgNO3  solution,  indicative  of  the  presence  of  chlorine 

or  chlorides. 

5.  Two   c.c.    diluted   as  in  (4),  and   put   in  a  test-tube, 
should  exhibit  no  turbidity  upon  the  addition  of  a  few  drops 

N 
of    —  BaCl2.2H2O    solution,  indicative   of   the   presence    of 

sulphuric  acid. 

6.  The   percentage   of  hyponitric   acid    present  may  be 

N 
determined    by   titrating   with    a   -       solution    of   potassium 

permanganate,  as  follows : 


42  LECTURES  ON  EXPLOSIVES. 

N 
Introduce  into  a  flask  a  known  quantity  of  —  solution  of 

potassium  permanganate  by  means  of  a  burette,  and  by 
means  of  an  accurate  pipette  add  2  c.c.  of  the  nitric  acid  to 
be  tested,  holding  the  lower  end  of  the  pipette  immediately 
over  the  permanganate  solution.  Shake  the  flask,  and  add  a 
sufficient  quantity  of  the  acid  to  entirely  eliminate  the  color 
of  the  solution.  Dilute  the  contents  of  the  flask  with  dis- 

N 
tilled  water,  and  add  more  of  the  —  solution,  with  frequent 

agitation,  until  the  contents  of  the  flask  retain  a  distinct  pink 

N 
color.      Each  c.c.  of  the  —  solution  is  equivalent  to  0.0046 

gm.  of  hyponitric  acid.  The  weight  of  hyponitric  acid  thus 
found,  divided  by  the  specific  gravity  of  the  acid  being 
tested  and  multiplied  by  100,  will  give  the  percentage  of 
hyponitric  monohydrate,  which  should  not  exceed  2  per  cent 
in  acid  used  in  the  manufacture  of  explosives. 

7.  The  value  of  nitric  acid  for  the  manufacture  of  explo- 
sives may  be  determined  in  terms  of  the  percentage  of  the 
monohydrate  it  contains,  as  follows : 

Introduce  2  gm.  of  the  acid  under  examination  into  a 
flask  fitted  with  a  ground-glass  stopper  and  having  a  capacity 
of  not  less  than  100  c.c.  Dilute  with  distilled  water,  and 

N 

titrate  with  a  —  solution  of  sodium   hydrate.      Each  c.c.  of 
10 

such  solution  is  equivalent  to  0.0063  gm.  of  the  mono- 
hydrate.  Either  phenol-phthalein  or  methyl-orange  may  be 

N 

used   as  an  indicator.     The  total  number  of   c.c.  of  the  — 

10 

solution  required  indicates  the  total  acidity  of  the  nitric 
acid,  from  which  the  percentage  of  hyponitric  acid  must  be 
deducted. 

7.  Charcoal. — Charcoal  is  described  as  the  residue  of  the 
destructive  distillation  of  wood,  in  which  process  the  hydrogen 
and  oxygen  of  the  wood  are  for  the  most  part  expelled  in  the 
forms  of  wood  naphtha  (CH4O),  pyroligneous  acid  (C2H4O2), 


INGREDIENTS   OF  EXPLOSIVES.  43 

carbonic  acid,  carbonic  oxide,  water,  etc.,  leaving  a  residue 
containing  a  much  larger  proportion  of  carbon  than  the 
original  wood,  and  therefore  capable  of  producing  a  much 
higher  temperature  by  its  combustion  with  the  saltpetre. 

The  process  is  conducted  in  closed  iron  retorts,  the  first 
result  being  the  driving  off  of  the  moisture  contained  in  the 
wood  until  a  temperature  of  about  284°  F.  is  reached,  when 
the  more  volatile  constituents  begin  to  distil  off. 

The  kind  and  quantity  of  charcoal  obtainable  varies  with 
the  kind  of  wood,  although  the  latter  varies  also  with  the 
temperature  and  duration  of  the  process  of  carbonization, 
diminishing  as  the  temperature  increases  and  increasing 
directly  with  the  length  of  time  of  charring.  The  percentage 
of  carbon  in  various  charcoals  varies  almost  to  as  great  an 
extent  as  the  charcoals  themselves,  and  increases  with  both 
the  temperature  and  yield. 

The  physical  properties  of  charcoal  also  vary  between 
wide  limits.  Thus,  charcoal  made  at  270°  C.  is  of  a  brown- 
ish-red color,  and  is  slightly  friable;  that  made  at  about  280° 
C.  is  much  darker;  at  340°  C.  it  becomes  black  ;  and  all  char- 
coals made  at  this  or  higher  degrees  of  temperature  are  called 
"  black  charcoals." 

Charcoal  made  at  about  430°  C.  has  a  smooth  fracture 
showing  the  texture  of  the  wood,  and  may  be  readily  pul- 
verized; that  made  between  1000°  and  1500°  C.  is  very 
black,  very  hard  and  brittle  ;  while  above  this  degree  of  heat 
there  results  a  very  hard,  tough  charcoal  which  emits  a  ringing 
metallic  sound  when  struck.  The  density  of  charcoal,  as  well 
as  its  hygroscopicity,  varies  with  the  temperature  of  charring, 
the  former  diminishing  from  1.507  at  150°  C.  to  1.406  at 
290°  C.,  from  which  point  it  increases  until  it  reaches  1500° 
C.,  where  its  density  is  1.869.  It  appears  that  the  higher 
the  temperature  the  less  hygroscopic  the  charcoal,  although 
this  point  has  not  yet  been  absolutely  determined. 

A  very  important  property  of  charcoal  requires  special 
attention,  and  that  is,  the  capacity  of  charcoal  to  absorb  and 
condense  gases  on  its  surface. 


OF  THE 


44  LECTURES   ON  EXPLOSIVES. 

The  condensation  of  gases  on  the  surface  of  charcoal  is 
always  attended  with  disengagement  of  heat,  and  if  this  action 
be  sufficiently  rapid  and  violent  it  may  result  in  raising  the 
temperature  to  the  ignition  point  of  the  charcoal.  This 
actually  occurs  whenever  freshly  prepared  charcoal  is  heaped 
in  considerable  quantities.  The  true  cause  of  this  phenomenon 
is  as  yet  unknown. 

In  recent  years  a  form  of  charcoal  has  been  used  in  the 
so-called  brown  or  cocoa  powders  which  differs  materially 
from  that  derived  from  wood.  It  is  made  by  subjecting  rye 
straw  to  the  action  of  superheated  steam,  by  means  of  which 
all  foreign  matter  is  extracted  and  the  carbonization  is  limited 
so  that  the  color  of  the  resulting  charcoal  is  that  of  chocolate. 

The  rye  straw  used  for  this  .purpose  is  carefully  selected, 
only  thick,  heavy  stalks  being  used.  The  ears,  etc.,  are  first 
removed  and  the  straw  is  stacked  in  the  open  air  until  thor- 
oughly dry,  and  is  then  introduced  into  the  retorts  and 
subjected  to  the  action  of  superheated  steam  for  several  hours. 

In  the  manufacture  of  brown  powders  in  the  United 
States  the  DuPont  Company  uses  various  forms  of  carbo- 
hydrates. This,  however,  and  the  preparation  of  charcoal 
for  use  as  an  ingredient  of  gunpowder,  will  be  alluded  to 
later. 

Tests  for  Charcoal. — In  the  laboratory  it  is  only  necessary 
to  determine  whether  the  charcoal  has  been  properly  charred, 
and  for  this  purpose  it  will  suffice  to  estimate  the  percentage 
of  ash  and  volatile  constituents;  incidentally  the  amount  of 
moisture  will  become  known,  and  is  applied  in  the  subsequent 
calculations. 

1.  Moisture. — Heat  in  a  drying-oven  at  150°  C.  5  gm.  of 
charcoal  previously  weighed  in  a  porcelain  crucible  (of  known 
weight)  until  the  weight  becomes  constant,  allowing  the  cru- 
cible to  cool  in  a  desiccator  between  each  weighing.      (The 
temperature  of  the  oven  should  be  raised  gradually.) 

2.  Ash. — Ignite  to  constant   weight    5    gm.    of    charcoal 
similarly  weighed  in  a  tared  crucible;  the  difference  in  weight 
will  be  the  ash,  whence  the  percentage  becomes  known. 


INGREDIENTS   OF  EXPLOSIVES.  45 

3.  Volatile  Constituents. — Place  the  crucible  containing 
the  charcoal  from  which  the  moisture  has  been  expelled  in  a 
clay  crucible,  surround  the  latter  crucible  with  charcoal,  and 
gradually  heat  it  until  its  sides  glow  brightly,  and  maintain 
this  degree  of  heat  for  half  an  hour.  Remove,  allow  to  cool, 
and  reweigh  the  porcelain  crucible.  The  loss  of  weight  will 
be  due  to  expulsion  of  the  volatile  constituents. 

8.  Sulphur.  (S). — Until  recently  all  of  the  sulphur  used 
in  the  manufacture  of  gunpowder  came  from  Sicily,  where  it 
occurs  naturally  in  a  limestone  formation,  the  mineral  as  it 
appeared  in  the  mine  containing  from  6  to  25  per  cent  of  sul- 
phur, although  it  at  times  ran  as  high  as  60  or  70  per  cent. 
The  sulphur  thus  obtained  contained  many  impurities,  and  it 
was  necessary  to  refine  it  before  using  it  as  an  ingredient  of 
explosives.  The  refining  process  is  described  later  under  the 
subject  of  gunpowder.  More  recently,  however,  the  sulphur 
used  for  this  purpose  is  obtained  from  the  residue  formed  in 
the  manufacture  of  soda,  which,  until  the  process  of  reclaiming 
the  sulphur  it  contained  was  discovered,  was  thrown  away. 
This  residue  consists  principally  of  calcium  sulphide,  and  the 
process  consists  essentially  of  treating  the  sulphide  with  water 
and  then  subjecting  it  to  the  action  of  carbonic  acid,  which 
converts  it  into  calcium  carbonate  and  sulphydric  acid.  The 
sulphydric  acid  is  conducted  into  gas-holders,  where  it  is 
mixed  with  air,  and  is  subsequently  burned  in  a  kiln,  the 
products  of  the  combustion  being  water  (in  the  form  of  steam) 
and  sulphur. 

At  ordinary  temperature  sulphur  is  a  solid  having  a  bright- 
yellow  color,  and,  according  to  the  manner  in  which  it  is  pre- 
pared, may  appear  in  the  form  of  oblique-rhombic  monoclinic 
crystals,  or  transparent  rhombic  octohedra.  It  is  insoluble  in 
water,  and  only  slightly  soluble  in  alcohol,  benzene,  and  fatty 
oils.  It  is,  however,  quite  soluble  in  carbon  bisulphide, 
which  property  is  utilized  extensively  in  examining  sulphur, 
and  in  separating  it  from  other  substances.  Its  specific  gravity 
is  2.087,  and  under  the  action  of  heat  it  behaves  very  curi- 
ously. At  in0  C.  it  melts;  at  H2°C.  it  appears  a  bright- 


4  LECTURES    ON  EXPLOSIVES. 

yellow  liquid;  at  140°  C.  it  becomes  dark  yellow  and  very 
viscous;  between  170°  and  200°  C.  it  becomes  dark  brown 
and  pasty ;  above  this  temperature  it  liquefies  again  until  it 
reaches  440°  C.,  when  it  boils,  evolving  reddish-brown  fumes. 
Formerly  it  was  supposed  that  the  principal  role  played  by 
sulphur  in  explosives  was  that  of  reducing  the  point  of 
ignition,  due  to  its  tendency  to  combine  with  oxygen  at  only 
a  moderately  elevated  temperature,  but  the  heat  disengaged 
by  sulphur  during  combustion  makes  it  a  far  more  impor- 
tant factor,  since  this  property  serves  to  greatly  increase  the 
volume  of  gases  evolved  during  explosion.  Although  a 
poor  conductor  of  electricity,  when  rubbed  a  strong  electric 
charge  is  developed — a  fact  that  must  be  considered  in  con- 
nection with  making  explosives  containing  sulphur,  since 
neglect  of  it  may  lead  to  the  ignition  or  even  explosion  of  the 
mixture. 

Tests  for  Sulphur. — Refined  sulphur  may  contain  as  im- 
purities earthy  matter,  together  with  traces  of  iron,  arsenic, 
and  antimony,  while  the  presence  of  sublimed  sulphur 
("  flowers  "),  even  in  traces,  serves  to  develop  an  acid  reaction. 

1.  Refined  sulphur  when  finely  pulverized  and  treated  with 
boiling  water  (distilled)  should  show  no  trace  of  acidity  when 
tested  with  litmus-paper. 

2.  The    earthy   matter   present    may    be    determined    by 
weighing  2   gm.   in  a  tared  porcelain  crucible,  igniting,  and 
placing  the  crucible  under  a  bell-jar  until  the  contents  of  the 
crucible  are  entirely  consumed. 

The  amount  of  residue  should  not  exceed  0.25  per  cent. 

3.  The  presence  of  iron  is  detected  by  treating  the  residue 
obtained  in  (2)  wit4i  hydrochloric  acid,  and  adding  a  few  drops 
of  potassium  ferrocyanide.      The  minutest   trace  of  iron  will 
develop  a  decidedly  blue  color. 

4.  The  presence  of  arsenic  and  antimony  may  be  detected 
by  means  of  the  Marsh  test,  or  by  any  of  the  various  tests 
characteristic  of  these  metals. 

9.  Sulphuric  Acid  (Hydric  Sulphate,  H2SO4). — The  proc- 
ess of  making  sulphuric  acid  was  discovered  about  four 


INGREDIENTS   OF  EXPLOSIVES.  47 

hundred  years  ago,  and  is  still  used  in  making  the  Nordhausen 
oil  of  vitriol,  or  fuming  sulphuric  acid.  It  consists  in  expos- 
ing iron  protosulphate  to  the  action  of  the  oxygen  of  the  air 
until  it  is  converted  into  the  basic  ferric  sulphate,  and  then 
drying  this  salt  and  distilling  it  in  earthenware  retorts,  ferric 
oxide  being  left  behind  in  the  retorts.  The  reactions  may  be 
represented  as  follows: 

6FeS04  +  03  =  2Fe,(S04),.FeA; 

Fe2(S04)3  +  2H2O  =  Fe303  +  2H2SO4  +  SO. 

The  sulphuric  acid  thus  obtained  differs  from  that  used  in 
making  explosives  by  its  fuming  upon  coming  into  contact 
with  the  air,  due  to  the  escape  of  a  little  sulphuric  anhydride, 
and  by  its  greater  specific  gravity  (1.900).  The  sulphuric  acid 
used  in  making  explosives  is  made  as  follows : 

A  mixture  of  sulphurous  acid  gas,  air,  steam,  and  a  little 
vapor  of  nitric  acid  is  introduced  into  a  leaden  chamber  con- 
taining a  layer  of  water.  The  nitric  acid  is  reduced  by  the 
sulphurous  acid  gas  to  the  state  of  nitrogen  monoxide  (NO), 
which  takes  up  oxygen  from  the  air  (forming  NOa)  and  gives 
it  to  the  sulphurous  acid  gas,  which  it  converts  into  sulphuric 
acid.  This  is  absorbed  by  the  water,  forming  diluted  H2SO4 , 
which  is  concentrated  by  evaporation  first  in  leaden  pans  and 
afterwards  in  glass  retorts  and  platinum  stills.  The  properties 
of  this  acid  are  very  characteristic.  Its  great  weight  (sp.  gr. 
1.842),  freedom  from  odor,  and  oily  appearance  distinguish 
it  from  any  other  liquid.  When  absolutely  pure  it  is  per- 
fectly colorless,  but  the  ordinary  acid  has  a  peculiar  gray  color, 
due  to  traces  of  organic  matter.  It  is  powerfully  corrosive, 
and  when  poured  upon  a  piece  of  wood  the  latter  is  at  once 
blackened.  It  possesses  very  great  affinity  for  water,  as  shown 
by  the  sudden  and  great  elevation  of  temperature  produced  on 
mixing  H2SO4  and  water.  This  latter  property  is  utilized  in 
the  laboratory  in  drying  substances  without  the  aid  of  heat ;  it 
is  also  turned  to  account  in  concentrating  nitric  acid,  or  in 
absorbing  the  water  produced  during  a  reaction  in  which  nitric 


4  LECTURES   ON  EXPLOSIVES, 

acid  plays  a  part,  thereby  keeping  the  latter  acid  up  to  its  full 
strength,  only  the  strongest  and  most  concentrated  acid  being 
used  for  this  purpose. 

Tests  for  Sulphuric  Acid.  —  I.  The  acid  should  be  clear 
and  colorless. 

2.  Determine  its  specific  gravity  as  in  the  preceding  test 
for  HNO3.      It  should  not  be  less  than  1.845  at  1S°  C. 

3.  Ten  drops  of  the  acid  evaporated  to  dryness  on  plati- 
num-foil should  leave  no  residue  indicative  of  the  presence  of 
metals. 

4.  Dilute  2  c.c.  of  the  acid  with  5  volumes  of  water.     No 
turbidity  should  appear  indicating  the  presence  of  lead. 

5.  A  more  characteristic  test  for  the  presence  of  lead  is 
the  formation  of  lead  iodide  in  the  form  of  a  yellow  precipitate 
upon  the  addition  of  potassium  iodide  to  even  dilute  solutions 
containing  lead ;   and  the  further  solution  of  this  precipitate 
upon  adding  boiling  water  only  to  separate  out  again  in  bril- 
liant spangles  upon  cooling. 

6.  Upon  diluting  2   c.c.   of  the  acid  with    10  volumes  of 
water,  acidifying  with  a  drop  of  HNO3,  and   adding  a  little 

N 
-  AgNO3  solution,  no  turbidity  should  appear  indicative  of 

chlorine  or  chlorides. 

7.  Traces  of    nitric   acid   remaining   from  the  process   of 
manufacture  may  be  determined  as  follows: 

One  part  of  carbolic  acid  (cryst.)  dissolved  in  four  parts  of 
H2SO4  and  diluted  with  two  parts  of  water,  should  produce  no 
reddish-brown  color,  which  turns  yellow  upon  the  addition  of 
(NH4)HO. 

8.  The  presence  of  iron  may  be  determined  by  diluting 
2  c.c.  of  the  acid  with  five  volumes  of  water  and  adding  a  few 
drops  of  potassium  ferrocyanide.      The  appearance  of  a  blue 
color  indicates  traces  of  iron. 

9.  Arsenic  (as  well  as  iron)  when  present  in  sulphuric  acid 
used  with  nitric  acid  in  the  process  of  nitration  reduces  the 
nitro-products,  and   should  therefore  not  exceed   more  than 
one   tenth  of  one   per  cent   in  amount.      To  detect  arsenic. 


INGREDIENTS   OF  EXPLOSIVES.  49 

dilute  I  c.c.  of  the  acid  with  10  c.c.  of  water,  and  add  2  c.c. 
of  CuSO4 ;  a  piece  of  pure  zinc  introduced  into  a  test-tube 
containing  5  c.c.  of  the  mixture  should  not  produce  arseniu- 
retted  hydrogen,  indicated  by  discoloring  a  strip  of  filter-paper 

N 

moistened  with  —  solution  of  AgNO3  suspended  in  the  test- 
10 

tube.      (The  tube  should  be  closed  with  a  perforated  cork.) 

10.  The  value  of  sulphuric  acid  is  determined  in  a  manner 
exactly  similar  to  that  used  in  the  valuation  of  nitric  acid, 

N 
i.e.,    titrate   with    a   —    solution   of    sodium   hydrate,    using 

N 
methyl-orange  as  an  indicator.      Each  c.c.  of  the  --  solution 

is  equivalent  to  0.0098  gm.  of  sulphuric  acid  monohydrate. 

10.  Hydrocarbons — Although  the  elements  carbon  and 
hydrogen  are  capable  of  combining  in  almost  infinite  propor- 
tions, presenting  various  forms  known  as  hydrocarbons,  it  is 
very  difficult  to  cause  them  to  combine  directly.  Hydro- 
carbons are  found  in  nature  generally  combined  or  mixed 
with  organic  substances,  from  which  they  are  separated  by 
means  of  fractional  distillation,  and  the  nature  of  the  result- 
ing product  depends  largely  upon  the  material  used  and  the 
degree  of  heat  applied  to  effect  decomposition.  Hydro- 
carbons containing  not  more  than  four  atoms  of  carbon  in 
their  molecule  are  generally  gaseous  at  ordinary  temperature ; 
if  the  molecule  contains  from  four  to  twelve  carbon  atoms,  it 
is  a  liquid,  and  those  containing  a  still  greater  number  of 
carbon  atoms  are  usually  solid. 

All  hydrocarbons  may  be  volatilized  without  decompo- 
sition, possess  peculiar  and  characteristic  odors,  are  insoluble 
in  water,  but  are  soluble  in  alcohol,  ether,  carbon  bisulphide, 
etc.  Apart  from  the  inflammable  and  explosive  gases,  only 
those  hydrocarbons  belonging  to  the  aromatic  series  are  of 
importance  in  the  manufacture  of  explosives. 

The  members  of  this  series,  of  which  benzene  may  be 
considered  the  type,  may  be  represented  by  the  general  for- 


5O  LECTURES   ON  EXPLOSIVES. 

mula  CM.HaM_6,  in  which  n  may  be  any  whole  number  not  less 
than  6. 

Benzene  (C6H6). — Benzene  occurs  in  petroleum,  but  its 
most  abundant  source  is  the  light  oil  obtained  in  the  distilla- 
tion of  coal-tar,  from  which  it  is  obtained  by  fractional  dis- 
tillation. A  distinction  is  now  recognized  between  benzene 
and  benzole,  the  latter  being  derived  from  coal-naphtha,  which 
has  a  lower  boiling-point  than  petroleum  or  coal-tar,  and  is 
therefore  the  first  or  lighter  products  distilled  over. 

Pure  benzene  is  a  brilliant  colorless  liquid,  exhaling  a 
powerful  odor  of  coal-gas;  it  boils  at  176°  F.,  and  is  very 
inflammable,  burning  with  a  smoky  flame.  It  mixes  readily 
with  alcohol  and  wood-spirit,  but  not  with  water. 

When  subjected  to  the  action  of  nitric  acid,  one  or  more 
atoms  of  hydrogen  are  replaced  by  the  corresponding  number 
of  nitryl  molecules  (NO9),  giving  rise  to  various  nitro-com- 
pounds,  which  will  be  considered  later.  Benzene  is  very 
volatile,  evolving  vapors  which  when  mixed  with  air  become 
explosive,  and  constituting  a  source  of  danger  which  is  often 
overlooked. 

Benzene  vapor,  being  much  heavier  than  air,  falls  to  the 
floor  upon  escaping  frorn  its  containing  vessel,  and  lies  there 
almost  unnoticed,  save  by  a  slight  odor  which  is  scarcely 
perceptible  in  a  laboratory,  until  brought  into  contact  with  a 
naked  flame,  with  the  result  of  a  sudden  and  violent  explosion. 
It  should  therefore  be  kept  in  well-stoppered  bottles,  and 
manipulated  either  in  a  hood  provided  with  sufficient  draught 
to  carry  off  the  vapor,  or  in  the  open  air. 

Test  for  Benzene. — Benzene  contains  very  few  impurities 
other  than  traces  of  other  hydrocarbons,  which  do  not  affect 
its  value  for  explosive  purposes  to  any  extent.  It  is,  how- 
ever, sometimes  necessary  to  determine  its  capacity  for  nitra- 
tion, which  may  be  done  as  follows:  Introduce  into  a 
fractional  distilling-flask  100  parts  of  the  benzene  to  be  tested, 
and  add  gradually  a  mixture  consisting  of  150  parts  of  nitric 
acid  (sp.  gr.  1.42)  and  200  parts  of  sulphuric  acid  (sp.  gr. 
1.84)  which  has  been  thoroughly  cooled.  This  is  best  done 


INGREDIENTS   OF  EXPLOSIVES.  51 

by  means  of  a  separatory  funnel  so  as  to  allow  the  acid  mix- 
ture to  run  in  drop  by  drop. 

During  the  introduction  of  the  acid  mixture  the  flask  is 
cooled  by  immersing  it  in  cold  water.  As  soon  as  all  of  the 
acid  has  run  into  the  flask,  the  flask  is  closed  by  a  perforated 
cork  through  which  a  thermometer  is  introduced,  and  when 
the  temperature  becomes  constant  the  flask  is  connected  with 
a  condensing  apparatus,  and  gentle  heat  is  applied  to  the  flask 
(preferably  steam  heat)  for  about  two  hours.  The  nitro-ben- 
zene  thus  formed  is  separated  from  the  acid  by  means  of  a 
separatory  funnel,  the  last  traces  being  removed  by  diluting 
the  acid  mixture  with  water  and  using  the  same  funnel.  The 
nitro-benzene  is  next  thoroughly  washed  with  water  and  a 
dilute  soda  solution,  and  finally  introduced  into  the  distilling- 
flask  again  (after  having  removed  the  water,  etc.),  and  distilled 
.at  a  temperature  of  about  150°  C. 

It  is  sometimes  necessary  to  nitrate  the  residue  a  second 
time  and  redistill.  Theoretically  100  parts  of  benzene  should 
yield  157.6  parts  of  nitro-benzene. 

12.  Toluene  (C7HB).  —  Toluene,   or    methyl-benzene,   is    a 
homologue  of  benzene,  from  which  it  is  derived  by  substituting 
for  one  atom  of  hydrogen  one  molecule  of  methyl,  CHS.      It 
was  originally  obtained  by  distillation  from  balsam  of  Tolu, 
but  is  now  prepared  from  tar  by  the  same  process.      Toluene 
resembles   benzene   very  closely    in    color    and    odor,    but   is 
slightly  heavier,  its  specific  gravity  being  0.882,  while  that  of 
benzene  is  0.878.      Another  point  of  difference  that  serves  to 
distinguish  these  two  substances  is  that,  whereas  benzene  crys- 
tallizes at  o°  C.,  toluene  does  not   solidify  at  —  20°  C.      The 
capacity  of  toluene  for  nitration  may  be  determined  similarly 
as  in  the  case  of  benzene. 

13.  Naphthalene  (C10H8). — Although  naphthalene  does  not 
belong  to  the  aromatic  series  of  hydrocarbons,  it  is  mentioned 
here  as  a  substance  which  has  been  largely  experimented  with 
as  a  probable  source  for  nitro-substitution  explosives. 

It  is  easily  obtained  in  a  pure  state  from  the  portions 
remaining  at  the  close  of  distillation,  by  simply  pressing  the 


52  LECTURES   ON  EXPLOSIVES. 

semi-solid  mass  to  remove  any  liquid  hydrocarbons,  and  boiling 
with  alcohol,  from  which  the  napthalene  crystallizes  on  cool- 
ing in  brilliant  pearly  flakes,  which  may  be  still  further  purified 
by  the  process  of  sublimation. 

Naphthalene  smells  strongly  of  coal-gas,  is  very  fusible 
(80°  C.)  and  inflammable,  burning  with  a  smoky  flame;  it  is 
insoluble  in  water,  but  dissolves  in  alcohol,  ether,  and  benzene. 
It  closely  resembles  benzene  in  its  chemical  relations,  and 
when  nitrated  gives  use  to  more  numerous  derivatives  than 
benzene,  all  of  which  have  been  experimented  with  in  the  more 
modern  explosives. 

14.  Carbohydrates — This  term  is  applied  to  a  class  of 
compounds  containing  hydrogen  and  oxygen  in  the  propor- 
tion to  form  water,  combined  with  six  atoms,  or  some  multi- 
ple of  six  atoms,  of  carbon.     They  are  remarkable  on  account 
of  the  number  of  instances  of  isomerism  they  present,  thus : 

The  formula  C6H12O6  may  represent  ordinary  glucose 
(dextrose),  grape-sugar  (laevulose),  mannitose,  or  inosite,  the 
latter  occurring  in  muscular  tissue,  in  the  lungs,  kidneys,  etc. 

C^H^Ojj  may  represent  saccharose  (common  sugar),  meli- 
tose,  maltose,  or  lactose  (milk-sugar). 

Finally,  C6HJOO6  represents  starch,  dextrine,  gums,  cellulose, 
or  glycogen,  which  is  found  exclusively  in  animals. 

All  of  these  substances  derived  from  vegetable  life  have 
been  used  from  time  to  time  in  explosives,  and  are  still  used 
to  a  limited  extent,  but  the  only  one  of  sufficient  value  to 
merit  more  than  passing  mention  is  cellulose. 

15.  Cellulose  (?z(C6H10O6),  perhaps  C18H3(1O1&).— This  sub- 
stance, also  called  Lignin,  constitutes  the  fundamental  material 
of  the  structure  of  plants:   it  is  employed  in  the  organization 
of  cells  and  vessels  of  all  kinds,  and  forms  a  large  proportion 
of  the  solid  parts  of  every  vegetable.      It  must  not  be  con- 
founded  with   ligneous  or   woody  tissue,   which   is   in   reality 
cellulose   with   other   substances    superadded,   encrusting   the 
walls  of  the  original  membranous  cells,  and  imparting  stiffness 
and  inflexibility.      Pure  cellulose,  on  the  other  hand,  has  the 
same  percentage  composition  as  starch  ;   but  woody  tissue  even 


INGREDIENTS   OF  EXPLOSIVES.  53 

when  freed  as  much  as  possible  from  coloring  matter  and  resin 
by  repeated  boiling  with  water  and  alcohol  yields,  on  analysis, 
a  result  indicating  an  excess  of  hydrogen  above  that  required 
to  form  water  with  the  oxygen,  besides  traces  of  nitrogen. 
Pure  cellulose  is  tasteless,  insoluble  in  water  and  alcohol,  and 
absolutely  innutritious;  it  is  not  sensibly  affected  by  boiling 
water,  unless  it  happens  to  have  been  derived  from  a  soft  or 
imperfectly  developed  portion  of  the  plant,  in  which  case  it  is 
disintegrated  and  rendered  pulpy.  It  is  acted  upon  slightly 
by  dilute  acids  and  alkalies,  but  in  their  more  concentrated 
forms  sulphuric  and  nitric  acids  transform  cellulose  into  other 
substances  differing  widely  from  the  original. 

Although  nearly  pure  cellulose  may  be  obtained  from 
various  sources,  that  used  in  explosives  is  generally  cotton, 
either  directly  from  the  pods,  or,  since  it  is  cheaper,  the 
"  cop-waste"  from  cotton-mills,  or  the  clippings  from  knitting- 
mills.  The  preparation  of  the  cotton  for  nitration  is  minutely 
described  later. 

16.  Alcohols — The  term  alcohol  is  now  applied  to  a  very 
great  class  of  substances  differing  greatly  in  chemical  and 
physical  properties.  Alcohols  may  be  considered  to  be  de- 
rived from  hydrocarbons  by  substituting  for  one  or  more 
atoms  of  hydrogen  an  equivalent  number  of  the  univalent 
radical  hydroxyl,  OH. 

They  are  therefore  hydroxides  of  hydrocarbon  radicals. 
According  to  the  number  of  hydrogen  atoms  replaced  by 
hydroxyl,  alcohols  are  monatomic,  diatomic,  triatomic,  etc. 

Alcohols  may  also  be  considered  as  derived  from  the  sub- 
stitution for  the  hydrogen  of  the  water-molecule  a  hydrocar- 
bon radical  of  the  paraffin  series  of  equivalent  atom-fixing 
power.  When  a  single  atom  of  hydrogen  is  thus  replaced, 
the  resulting  alcohol  is  called  monatomic,  or  monohydric;  if 
two  H  atoms  are  replaced,  the  alcohol  is  diatomic  or  dihydric  ; 
etc. 

Thus  monohydric  alcohols  may  be  considered  as  derived 
by  substituting  the  univalent  radical  of  a  hydrocarbon  of  the 
paraffin  series  (formed  by  the  loss  of  a  single  atom  of  H)  for 


54  LECTURES   ON  EXPLOSIVES. 

one  half  of  the  hydrogen  contained  in  a  single  molecule  of 
water;  e.g.,  methyl,  (CH3)',  replacing  one  atom  of  H  in  H2O 
to  form  methyl-alcohol,  CH3.HO,  or  ethyl,  (C2H6)',  replacing 
an  atom  of  H  to  form  ethyl-alcohol,  C2HB.HO,  etc. 

Similarly,  when  a  bivalent  radical  of  the  same  series 
formed  ih  a  similar  manner  replaces  two  atoms  of  H  con- 
tained in  a  double  molecule  of  water,  the  derived  alcohol  is 
dihydric;  e.g.,  etherne,  (C2H4)",  replacing  two  atoms  of  H  in 
H,(HO)a  to  produce  ethane-alcohol,  or  glycol,  C2H4(OH)2. 
Finally,  as  an  example  of  the  trihydric  alcohol,  we  may  con- 
sider propenyl-alcohols,  or  glycerol,  or  glycerine  derived  from 
propane,  C8H8 ,  by  replacing  three  atoms  of  H  in  a  treble 
molecule  of  water,  H3(HO)3,  by  the  trivalent  radical,  propenyl, 
(C.H.)'". 

Ethyl-alcohol. — This  monohydric  alcohol  is  the  one  gen- 
erally referred  to  by  the  term  alcohol  in  common  acceptation, 
and  is  one  of  the  most  important  substances  in  its  application 
to  explosives,  being  used  either  alone  or  in  combination  with 
other  alcohols  or  ethers  as  a  solvent.  It  is  usually  obtained 
by  the  fermentation  of  glucose,  or  grape-sugar,  excited  by 
yeast. 

It  possesses  a  characteristic  odor  and  burning  taste ;  when 
pure  it  is  transparent  and  colorless;  it  freezes  at  —  130°. 5  C., 
boils  at  about  78°  C.,  is  easily  inflammable,  burning  with  a 
pale-blue  smokeless  flame.  It  quickly  evaporates  when 
exposed  to  the  air,  from  which  it  also  absorbs  water.  It 
mixes  with  water  in  all  proportions,  and,  next  to  water,  is  the 
most  valuable  of  all  simple  solvents.  Its  solvent  power,  how- 
ever, depends  upon  its  strength,  which  must  be  accurately 
known  or  determined.  The  strength  of  alcohol  is  estimated 
from  its  specific  gravity.  The  specific  gravity  of  absolute 
alcohol  at  15°  C.  is  0.794;  rectified  spirit  has  a  specific 
gravity  of  0.838  and  contains  84  per  cent  of  alcohol;  proof 
spirit  has  a  specific  gravity  of  0.92  and  contains  only  49  per 
cent  of  alcohol. 

The  following  rule  of  thumb  is  given  by  Bloxam  for  cal- 
culating the  approximate  percentage  of  alcohol  from  its 


INGREDIENTS   OF  EXPLOSIVES.  55 

specific  gravity:  If  above  0.9493,  multipty  the  difference 
between  the  specific  gravity  and  unity  by  704;  if  below 
0.9398,  subtract  the  specific  gravity  from  this,  multiply  by 
480,  and  add  40. 

17.  Glycerine  (C,H5  (OH)3). — Glycerine,  or  glycerol,  or 
propenyl-alcohol,  may  be  obtained  from  nearly  all  of  the 
natural  fats,  and  is  also  formed  during  the  alcoholic  fermenta- 
tion of  sugar.  Glycerine  is  now  largely  prepared  by  the 
decomposition  of  fatty  substances  by  means  of  superheated 
steam.  Thus  prepared  it  is  obtained  in  great  purity.  It  is 
a  nearly  colorless  and  very  viscid  liquid  of  specific  gravity 
1.25.  When  quite  pure  and  anhydrous  it  crystallizes  on 
exposure  to  a  very  low  temperature,  especially  if  agitated,  as 
in  railroad  transport.  The  crystals  are  monoclinic,  perfectly 
colorless,  and  melt  at  60°  F.  It  has  an  intensely  sweet  taste, 
and  mixes  with  water  in  all  proportions ;  its  solution  does 
not  undergo  alcoholic  fermentation,  but  when  mixed  with 
yeast,  and  kept  in  a  warm  place,  it  is  gradually  converted  into 
propionic  acid.  Glycerine  is  neutral  to  vegetable  colors; 
heated,  it  volatilizes  in  part,  darkens  and  decomposes,  giving 
off  among  other  products  a  substance  called  acrolein,  (C3H4O), 
having  an  intensely  pungent  odor. 

Glycerine  has  a  sweetish  taste  and  is  of  syrupy  consis- 
tency; its  specific  gravity  at  12°  C.  is  1.269,  from  which  it 
should  differ  but  little  (1.262)  when  used  in  making  nitro- 
glycerine. Pure  glycerine  solidifies  and  becomes  gummy  at 
—40°  C.,  is  slightly  volatile  at  100°  C.,  and  boils  at  290°  C. 
It  absorbs  water  from  the  air,  is  soluble  in  all  proportions  in 
water  and  alcohol,  but  is  insoluble  in  ether. 

It  possesses  very  extensive  solvent  powers,  which  prop- 
erty is  next  in  importance  to  its  capacity  for  nitration,  in  its 
relation  to  explosives. 

TESTS  FOR  GLYCERINE. — On  account  of  the  danger  arising 
from  the  formation  of  very  unstable  explosives  during  the 
process  of  nitration  of  impure  glycerine  it  is  necessary  to 
examine  it  carefully. 

I.  For  the  Presence  of  Free  Acids. — Dilute  2   c.c.  with  an 


56  LECTURES   ON  EXPLOSIVES. 

equal  volume  of  distilled  water,  and  shake  for  a  few  minutes. 
Test  with  litmus-paper.      Reaction  should  be  neutral. 

2.  For  the  Presence  of  Carbonaceous  Matter. — Put  4  or  5 
drops  in  a  watch-crystal,   and  heat  gently.      It  should  burn 
with  a  pale-blue  flame,  evolving  a  sweetish  to  pungent  odor, 
and  leave  a  mere  trace  of  carbonaceous  residue. 

3.  For  the   percentage   of   carbonaceous   matter  weigh   5 
gms.  in  a  porcelain  crucible,  and  heat  gently  until  it  inflames. 
Remove  the  source  of  heat  until  the  glycerine  is  consumed, 
and   ignite  the  residue  thoroughly  (to  constant  weight),  and 
weigh  the  remaining  ash.      Distilled  glycerine  should  not  yield 
more  than  o.  i  per  cent  of  ash. 

4.  For  the  Presence  of  the  Higher  Fatty  Acids. — Dilute  as  in 
(i),  and  treat  with  a  current  of  N3O4.      It  should  remain  clear 
and  give  no  flocculent  precipitate. 

5.  For  the  Presence  of  Butyric  Acid. — Mix  2  c.c.  with  5  or  6 
drops  of  dilute  H2SO4.      There   should  be   no  odor  of  sweat 
when  the  mixture  is  rubbed  between  the  hands. 

6 .  For  the  Presence  of  A  crolein .  — Diluteasin(i),  and  t  reat 
with  a  normal  solution   of  AgNO3.      It  should  give   no  white 
precipitate  (which  blackens  on  standing  or  boiling)  within  24 
hours. 

7.  For  the  Presence  of  Formic  Acid. — Dilute  as  in  (i),  and 
treat  with  (NH4)Ag(NO3)4  (obtained  by  precipitating  Ag  from 
a  normal  solution  of  AgNO3  by  adding  NH3  and  redissolving 
the  precipitate)  at  ordinary  temperature  and  in  the  dark.      It 
should  give  no  black  precipitate  within  one  half-hour. 

8.  For  the  Presence  of  Glucose. — Dilute  as  in  (i),  mix  with 
an  equal  volume  of  KHO,  and  heat  on  water-bath.      It  should 
not  become  brown,  and  upon  the  addition  of  a  few  drops  of 
CuSO4  (solution)  it  should  give  no  precipitate. 

9.  For  the  Presence  of  Cane-sugar. — Mix  with  5  volumes 
of  HaO  and  one  half-volume  of  cone.  HC1,  and  heat  to  70°  or 
80°  C.  for  10  minutes.      When  heated  with  Fehling's  solution 
for  5  minutes  it  should  not  be  sensibly  reduced. 

10.  For  the  Presence  of  Organic  Ammonias. — Mix  3   c.c. 
with  an  equal  volume  of  KHO  in  a  test-tube,  and  introduce 


INGREDIENTS   OF  EXPLOSIVES.  57 

into  the  tube  above  the  mixture  a  glass  rod  dipped  in  HC1. 
No  fumes  should  be  given  off. 

1 1.  For  the  Presence  of  Gums  and  Analogous  Substances. — 
Mix  3  c.c.  with  an  equal  volume  of  a  mixture  of  2  parts  of 
ether  and  I  part  of  alcohol.      The  mixture  should  remain  per- 
fectly clear  and  uniform. 

12.  For  the  Presence  of  Copper,  Lead,  etc. — Dilute  as  in  (i), 
acidulate  with  HC1,  and  treat  with  SH2.      It  should  not  be- 
come discolored  nor  yield  a  precipitate. 

13.  For  the  Presence  of  Iron,  Zinc,  etc. — Make  alkaline  by 
the  addition  of  NH8,  and  treat  with  ammonium  chloride  and 
sulphydric  acid.      It  should  remain  clear  and  colorless. 

14.  For  the  Presence  of  HCl  and  Chlorides. — Dilute  as  in 
(i),  acidulate  with   HNO3,  and   treat  with  AgNO,  (solution). 
It  should  give  no  precipitate. 

1 5 .  For  the  Presence  of  H^SO^  and  Sulphates. — Dilute  as  in 
(i),  acidulate  with  HCl,  and  treat  with  BaCl2  (solution).      It 
should  give  no  precipitate. 

1 6.  For  the  Presence  of  Albuminous  and  Coloring  Matters. 
Dilute  with  2  volumes  of  H2O,  neutralize  carefully  with  acetic 
acid,  expel  the  CO2  by  heat,  and  allow  to  cool.      When  cool 
treat  with  basic  lead  acetate.      It  should  give  no  precipitate. 

17.  For  tJie  Presence  of  Calcium  Salts. — Dilute  as  in  (i), 
and  treat  with  ammonium  oxalate.      It  should  give  no  precipi- 
tate. 

1 8.  For  the  Presence  of  Oxalic  Acid. — Dilute  as  in  (i),  and 
treat  with  CaCl2  and  sodium  acetate.  It  should  give  no  pre- 
cipitate. 

18.  Ethers. — Ethers  may  be  derived  from  the  alcohols  by 
substituting    an    alcohol-radical    for    the    hydrogen     of    the 
hydroxyl  group,  (OH);   e.g.,  methylic  ether  may  be  obtained 
by  acting  upon  methyl-alcohol    first   with    metallic   sodium, 
and   then    decomposing   sodium    methylate    thus  formed    by 
means  of  methyl    iodide.      The  reactions  may  be  represented 
as   follows,  and  in   the  final  result    it  will  be  seen  that  the 
hydrogen  of  hydroxyl  in  the  original  alcohol  has  been  replaced 
by  the  univalent  alcohol-radical  CH3: 


$  LECTURES  ON  EXPLOSIVES. 

CH3.OH  +  Na  =  CHs.ONa. 
CH,.ONa+  CH.I  =  CH3.O.CH3  +  Nal. 

Ethylic  Ether  (C2H5.O.C2H6)._This  is  also  called  sul- 
phuric ether  from  its  method  of  preparation,  which  consists 
essentially  in  decomposing  alcohol  with  concentrated  sul- 
phuric acid,  and  subsequently  rectifying  the  crude  product. 
Before  being  used  as  a  solvent  it  must  be  concentrated  and 
all  traces  of  alcohol  removed. 

Pure  ether  is  a  perfectly  clear,  colorless  liquid,  possessing 
a  characteristic  odor,  and  having  a  specific  gravity  of  0.700 
at  15°  C.  It  boils  at  34°. 9  C.,  and  evaporates  rapidly  in  air, 
yielding  a  very  heavy  vapor  (sp.  gr.  2.59)  which  is  exceed- 
ingly inflammable,  and  when  mixed  with  air  highly  explosive, 
a  property  that  renders  it  very  dangerous. 

It  is  sparingly  soluble  in  water,  but  mixes  with  alcohol  in 
all  proportions.  Its  use  in  connection  with  explosives  is 
limited  to  its  solvent  powers,  since,  either  alone  or  with  alco- 
hol, acetone,  or  chloroform,  it  readily  dissolves  many  organic 
substances,  nitroglycerine,  guncotton,  nitro-benzene,  etc. 

The  only  tests  necessary  to  be  applied  to  ether  are  for  its 
degree  of  concentration  and  adulteration ;  the  former  being 
determined  by  means  of  its  specific  gravity,  and  by  testing 
for  acidity,  which  is  quickly  developed  by  the  presence  of 
water  or  alcohol  on  account  of  absorption  of  oxygen  ;  the  lat- 
ter is  readily  detected  by  evaporating  a  few  drops  upon  a  per- 
fectly clean  piece  of  platinum-foil  or  watch-crystal. 

Acetic  Ether  (C2HSO.O.C2HB). —  Until  recently  acetic 
ether  was  very  extensively  used  as  a  solvent  in  the  manufac- 
ture of  smokeless  powders,  and  its  use  is  still  retained  to  some 
extent. 

It  is  prepared  practically  by  distilling  alcohol  together 
with  sodium  acetate  and  concentrated  sulphuric  acid.  Thus 
prepared  it  contains  traces  of  acid  which  are  eliminated  by 
agitation  with  an  alkaline  carbonate. 

Acetic  ether  resembles  ordinary  ether  in  appearance,  but 
possesses  a  strong  odor  of  cider;  its  specific  gravity  is  0.910; 


INGREDIENTS   OF  EXPLOSIVES.  59 

it  boils  at  77°.  5  C.,  is  sparingly  soluble  in  water,  and  should 
be  perfectly  neutral  in  its  reaction  with  litmus. 

19.  Acetone. — In  its  present  acceptation,  acetone  refers 
to  one  particular  ketone  or  acetone,  namely,  dimethyl-ketone 
or  pyro-acetic  spirit,  having  the  composition  CH3.CO.CH,. 

As  a  class,  however,  the  acetones  are  derived  from  the 
acids  by  substituting  for  one  molecule  of  hydroxyl,  OH,  of 
the  acid  group,  CO. OH,  another  radical,  usually  a  hydrocar- 
bon radical  of  the  alcohols;  e.g.,  by  substituting  methyl,  CH3, 
for  hydroxyl,  OH,  in  acetic  acid,  CH3.CO.OH,  we  have  di- 
methyl-ketone, or  ordinary  acetone,  CH3.CO.CH3.  Acetone 
may  be  obtained  from  the  distillation  of  wood,  but  commer- 
cially \t  is  prepared  by  distilling  the  various  acetates,  princi- 
pally the  calcium  acetate,  which  is  extensively  exported  from 
this  country  for  the  purpose.  The  crude  distillate  is  treated 
with  a  saturated  solution  of  hydrosodic  sulphite,  again  dis- 
tilled with  sodium  carbonate,  and  subsequently  concentrated 
by  means  of  calcium  chloride. 

Acetone  is  a  colorless,  volatile,  highly  fragrant  liquid, 
having  a  specific  gravity  of  0.81  at  15°  C.  and  boiling  at  56°. 3 
C.  It  is  inflammable,  burning  with  a  luminous  flame,  and 
its  vapor  mixed  with  air  becomes  very  explosive.  It  mixes 
with  water  in  all  proportions;  dissolves  camphors,  resins,  and 
various  organic  compounds;  and  is  one  of  the  most  extensively 
used  solvents  in  making  explosives,  especially  smokeless  pow- 
ders. On  account  of  its  extensive  use  the  following  tests  for 
its  purity  are  suggested  : 

Tests  for  Acetone. — I.  It  should  be  perfectly  clear  and 
colorless. 

2.  When  mixed  with  an  equal  volume  of  water  and  thor- 
oughly shaken,  it  should  give  no  precipitate  nor  show  any 
turbidity. 

3.  It  should  be  perfectly  neutral. 

4.  If  traces  of  acidity  be  detected,  the  percentage  estimated 
as  acetic  acid  should  not  exceed  0.0025   Per  cent  when  tested 
as  follows: 

Dilute  50  c.c.  of  acetone  with  an  equal  volume  of  distilled 


6O  LECTURES   ON  EXPLOSIVES. 

N  i 

water;  and  titrate  with  —  solution    of    sodium     carbonate, 

100 

using  phenol-phthalein  as  an  indicator  (i  gm.  to  i  litre  of  50$ 
alcohol).    Each  c.c.  of  the solution  is  equivalent  to  0.0006 

gm.  of  acetic  acid. 

5.  Its  specific  gravity  at  15°  C.  must  be  at  least  0.7965. 

6.  Distilled  at  a  temperature  between  56°. 2  and  56°. 4  C., 
98  per  cent  must  pass  over  into  the  receiver. 

7.  Tested  with  the  weight-thermo-alcoholimeter,  it  should 
show  at  least  98  per  cent. 

8.  It   should    contain    no    more    than    o.  I    per    cent    of 
aldehyde,  which  may  be  estimated  as  follows : 

Prepare  a  solution  by  dissolving  3  gm.  AgNO3  and  3 
gm.  NaHO  in  distilled  water,  adding  20  gm.  (NH4)OH  (sp. 
gr.  0.9),  and  make  solution  up  to  100  c.c. 

This  solution  is  known  as  the  silver  solution,  and  should  be 
kept  in  a  dark  place. 

Dissolve  10  c.c.  of  the  acetone  to  be  tested  in  10  c.c.  of 
distilled  water,  add  2  c.c.  of  the  silver  solution,  and  allow  to 
stand  in  a  dark  place  for  fifteen  minutes. 

Decant  from  the  reduced  silver  the  supernatant  liquid, 
and  test  the  latter  for  excess  of  silver  by  adding  carefully 
(NH4)2SO4  solution,  which,  in  case  of  any  unreduced  silver 
being  present,  will  produce  a  brownish  turbidity  in  the  liquid 
or  throw  down  a  brownish-black  precipitate.  The  presence 
of  unreduced  silver  indicates  the  presence  of  less  than  o.  i  per 
cent  of  aldehydes  in  the  acetone. 

9.  The    percentage    of    acetone    estimated   by   the    iodo- 
metric  method  should  not  be  less  than  98  per  cent. 

This  method  is  as  follows : 

Dissolve  8  gm.  of  acetone  in  equal  volume  of  water,  and 
make  the  solution  up  to  one  litre.  Decant  10  c.c.  of  this 
solution  into  a  glass  bottle  having  a  capacity  of  not  less  than 
250  c.c.  and  fitted  with  a  ground-glass  stopper.  Introduce 

N 
into  this  bottle  50  c.c.  of  —  solution  of  sodium  carbonate  and 


INGREDIENTS   OF  EXPLOSIVES.  6 1 

50  c.c.  of  —  or  —  solution  of  iodine,  close  the  bottle  snugly, 

5         4 
and  shake  for  one-half  hour.      Next  remove  the  stopper  and 

N 
introduce   into    the   bottle    50    c.c.   of  —   HC1,    washing    the 

N 
stopper  with  the  acid  as  it  is  poured  in.      Titrate  with  a  — 

solution  of  sodium  thiosulphate  until  the  color  produced 
upon  the  addition  of  clear  starch  paste  entirely  disappears. 
The  number  of  c.c.  of  the  sodium  thiosulphate  solution 
equivalent  to  the  iodine  solution  must  be  deducted  from  the 

N      N 
50  c.c.  of  —  or  —  solution  of  iodine  previously  added.      413. 8 

4        5 

N  N 

c.c.  of  the  —  solution,  or  517.26  c.c.  of  the  —   solution,  are 

4  5 

equivalent  to  one  gramme  of  acetone. 

20.  Camphor,  Vaseline,  Paraffin  Wax,  etc. — These  sub- 
stances are  largely  used  in  the  manufacture  of  explosives, 
together  with  others  too  numerous  to  mention ;  but  their 
effect  is  rather  mechanical  than  chemical,  and  is  as  a  rule 
overestimated. 

Camphor  (C10H16O). — The  various  camphors  appear  to  be 
derived  from  hydrocarbons  by  a  process  of  oxidation,  all  of 
them  being  rich  in  carbon  and  hydrogen  with  a  relatively  low 
percentage  of  oxygen. 

Common  camphor  is  found  in  the  wood  of  the  camphor- 
laurel,  from  which  it  is  extracted  by  distillation  with  water 
and  purified  by  sublimation  in  vessels  containing  lime.  It 
vaporizes  at  the  ordinary  temperature  of  the  air,  crystallizing 
in  brilliant  octahedra. 

It  fuses  at  175°  C.,  boils  at  204°  C.,  and  is  quite  inflam- 
mable, burning  with  a  thick  smoky  flame.  Its  specific  grav- 
ity is  0.996;  it  is  practically  insoluble  in  water,  but  dissolves 
readily  in  alcohol  and  ether  as  well  as  in  nitroglycerine. 

Camphor  is  no  longer  used  as  an  ingredient  of  smokeless 
powders,  but  enters  to  some  extent  in  various  dynamites, 


62  LECTURES   ON  EXPLOSIVES. 

especially  those  of  the  gelatine  variety,  in  which  it  acts  as  a 
desensitizing  agent. 

Vaseline,  or  Mineral  Jelly. — Vaseline  is  one  of  the  prod- 
ucts of  the  distillation  of  petroleum,  passing  over  at  a  tem- 
perature above  200°  C.,  and  generally  consists  of  a  mixture 
of  two  or  more  hydrocarbons  of  practically  the  same  melting- 
and  boiling-points.  It  may  also  be  obtained  from  ozokerite 
(mineral  wax),  which  is  found  in  large  quantities  in  Galicia, 
Hungary,  and  Russia. 

Pure  vaseline  is  a  soft,  yellowish,  greasy  substance  that 
melts  at  32°  C.,  flashes  at  about  400°  F.,  and  at  100°  F.  has 
a  specific  gravity  of  about  0.90. 

It  is  a  very  stable  substance,  preserves  a  neutral  reaction 
under  widely  varying  conditions,  and  is  largely  used  in 
making  smokeless  powders,  especially  in  the  manufacture  of 
the  English  service  powder,  cordite. 

According  to  the  English  specifications,  vaseline  for  use 
in  making  cordite  must  stand  successfully  the  following  tests: 

1.  It  must  be  free  from  all  traces  of  acidity. 

2.  It  must  be  free  from  all  traces  of  foreign  (especially 
mineral)  matter. 

3.  Heated  for  twelve  hours  over  a  water-bath  (100°  C.), 
it  must  not  lose  more  than  0.2  per  cent  in  weight. 

4.  Its  specific  gravity  at  100°  F.  must  not  be  less  than 
0.87. 

5.  Its  flashing-point  must  be  at  least  400°  F. 

Paraffin  Wax. — Paraffin  wax  contains  more  carbon  than 
vaseline,  and  appears  as  a  crystalline  solid.  It  is  variously 
obtained,  and,  depending  upon  the  method  of  its  preparation, 
it  varies  in  degree  of  hardness,  melting-point,  and  other 
properties.  It  often  develops  an  acid  reaction,  and  must  be 
melted  before  being  incorporated  in  explosives.  It  is  insolu- 
ble in  water,  but  yields  to  the  action  of  gasolene,  which, 
however,  introduces  a  source  of  danger  in  manipulation. 

Paraffin  is  used  quite  largely  in  the  manufacture  of  dyna- 
mites ;  but  its  use  in  smokeless  powders  has  been  practically 
abandoned. 


INGREDIENTS   OF  EXPLOSIVES.  63 

Various  other  organic  compounds,  such  as  resins,  glycer- 
Ides,  oils,  and  fats,  have  been  experimented  with  in  various 
forms  too  numerous  to  mention  in  a  work  of  limited  scope, 
their  function  being  principally  to  aid  in  incorporating  other 
ingredients,  to  moderate  the  action  of  the  explosive,  to  act  as 
lubricants  in  the  bore  of  the  guns,  and  for  other  purely  hypo- 
thetical purposes. 

21.  Kieselguhr,  Randanite,  etc. — The  first  substance 
used  to  absorb  nitroglycerine  and  thereby  transform  the 
explosive  from  the  liquid  to  solid  state  was  kieselguhr,  and 
for  an  absolutely  inert  absorbent  (or  dope,  as  it  is  technically 
known)  this  material  has  never  been  excelled. 

Ordinary  kieselguhr  consists  of  63  parts  of  soluble  silica, 
1 8  parts  of  organic  matter,  n  parts  of  sand  and  clay,  and  8 
parts  of  water.  Its  principal  sources  are  the  Luneburg  moors 
near  Unterluss,  between  Bremen  and  Hanover,  and  a  recently 
discovered  deposit  of  vast  extent  near  Richmond,  Virginia, 
U.  S.  A.  As  found  naturally,  kieselguhr  is  a  soft  grayish- 
white  or  reddish-white  material,  gritty  to  the  touch,  and 
readily  crumbling  to  pieces  under  pressure.  The  organic 
constituent  consists  of  the  decomposed  shells  of  myriads  of 
diatoms,  which  preserve  their  cellular  formation  even  after 
the  process  of  calcination  to  which  kieselguhr  is  subjected 
before  being  used  as  an  absorbent  for  explosives.  Each 
particle  therefore  acts  as  a  reservoir  for  the  liquid,  which  it 
retains  with  great  pertinacity,  the  best  varieties  of  kieselguhr 
being  capable  of  absorbing  and  retaining  as  much  as  82  per 
cent  of  nitro-glycerine. 

Randanite  consists  principally  of  decayed  feldspathic 
rocks,  and  was  used  as  a  substitute  for  kieselguhr  by  the 
French  during  the  war  of  1870.  As  an  absorbent  it  is  greatly 
inferior  to  kieselguhr  in  every  respect. 

Tripoli,  coal-dust,  saw-dust,  various  alkaline  carbonates, 
etc.,  have  been  experimented  with  for  the  same  purpose,  and 
will  be  referred  to  subsequently. 


LECTURE  IV. 

CLASSIFICATION  OF  EXPLOSIVE  MIXTURES.       EXPLOSIVE  MIX- 
TURES   OF    THE    NITRATE    CLASS. 

EXPLOSIVE  mixtures  may   be  defined  as  the   mechanical 
(  incorporation  of  two  or  more  ingredients  one  of  which  must 
be  a  combustible  and  at  least  one  other  a  supporter  of  com- 
bustion.     Such  mixtures  have  been  divided,  according  to  the 
nature  of  the  oxidizing  ingredient,  into  two  principal  classes, 
.  the  nitrate  class  and  the  chlorate  class. 

Explosive  Mixtures  of  the  Nitrate  Class. — In  this 
class  any  nitrate  may  be  utilized,  although  the  majority  of 
such  chemical  compounds  are  of  but  little  practical  value,  as 
already  indicated.  On  account  of  the  force  with  which  the 
oxygen  is  held  in  combination  in  the  nitrates,  it  requires  a 
powerful  disturbing  cause  to  separate  it  from  the  other  ele- 
ments; hence  this  class  of  explosives  does  not  decompose 
very  readily;  their  action  is  gradual;  they  are  not  sensitive 
to  friction  or  percussion,  and  therefore  they  are  compara- 
tively safe. 

The  formation  of  the  nitrates  in  nature  has  been  con- 
sidered very  obscure,  and  any  explanation  of  natural  nitrifica- 
tion involves  the  consideration  of  many  principles  which  are 
themselves  but  imperfectly  understood. 

It  is  now  generally  accepted  that  the  natural  nitrates  are 
formed  by  the  slow  oxidation  of  the  nitrogenous  organic  com- 
pounds, effected  by  the  oxygen  of  the  air  with  the  aid  of 
water  and  of  an  alkaline  or  earthy  carbonate. 

64 


CLASSIFICATION   OF  EXPLOSIVE   MIXTURES,  65 

Until  recently  it  was  believed  that  the  role  played  by  the 
nitrates  in  explosives  was  solely  that  of  oxidizers,  and  that, 
other  things  being  equal,  the  efficiency  of  a  nitrate  depended 
upon  the  percentage  of  oxygen  it  contained.  In  the  light  of 
thermochemistry,  we  know  that  other  and  perhaps  more  im- 
portant considerations  enter  the  problem,  and  that,  in  addi- 
tion to  the  amount  of  oxygen,  the  available  percentage  of 
this  element,  as  well  as  the  heat  of  formation  of  the  salt 
itself,  is  of  first  importance. 

Of  the  various  nitrates  experimented  with,  the  potassium' 
salt,  or,  as  it  is  commonly  known,  ''saltpetre,"  or  'k  nitre," 
is,  for  reasons  already  given,  best  adapted  for  use  in  the 
manufacture  of  explosives. 

It  is  the  oxidizing  agent  used  in  the  manufacture  of  gun- 
powder, which  may  be  taken  as  the  representative  of  this 
class  of  explosive  mixtures. 

Gunpowder. — This  explosive  is  a  very  intimate  mixture  of 
potassium  nitrate  (nitre),  sulphur,  and  charcoal,  which  do  not 
act  upon  each  other  at  the  ordinary  temperature,  but  when 
heated  together  arrange  themselves  into  new  forms,  evolving 
a  very  large  amount  of  highly  heated  gas.  These  three  in- 
gredients may  be  mixed  in  greatly  varying  proportions,  each 
mixture  being  explosive,  but  there  must  be  evidently  some 
particular  proportions  which  will  produce  the  most  effective 
powder. 

Experience  has  shown  that  a  powder  containing 

KNO3 75  parts 

C 15      " 

S 10      " 

100 

is  mixed  in  the  best  proportions,  and  until  recently  the  ma- 
jority of  military  nations  adopted  it. 

The  percentage  of  the  several  ingredients  in  the  service 
powders  adopted  by  the  principal  military  nations  at  present 
are  given  below. 


66 


LECTURES   ON  EXPLOSIVES. 
RIFLE-POWDER. 


Nitre. 

Sulphur. 

Charcoal. 

Austro-  Hungary  .  .  .  .         

7e  .0 

IO  O 

j  e    o 

Belgium     

7c  .  c 

12.  0 

12    f, 

7c  .0 

IO.O 

15  .O 

England  

7c  .0 

IO   O 

IE    o 

7^  .O 

IO   O 

i";  .0 

74-O 

IO.O 

16.0 

Holland  

7O.  O 

Mo 

16  o 

7S-O 

IO.O 

15.0 

75  .O 

12.  5 

12.5 

Portugal  

7e  .  7 

IO.  7 

H    6 

7S  -O 

]O   O 

JCQ 

Spain   

7c    o 

12    ^ 

12    ^ 

Sweden  

7C  .0 

IO   O 

1^    O 

75  .0 

IT  .O 

I4O 

Turkey     .        .        . 

7c    o 

IO    O 

]  C     y 

United  States  

7S    O 

IO.O 

ICQ 

The  proportions  thus  adopted  in  service  powders  are  not 
such  as  tend  to  produce  the  most  complete  combustion  nor 
the  maximum  heat,  but  form  a  compromise.  It  is  believed 
that  better  and  more  uniform  results  would  be  obtained  from 
powders  in  which  the  ingredients  are  incorporated  in  propor- 
tions to  produce  the  maximum  of  these  two  effects;  an  end, 
however,  it  may  be  said,  attainable  only  through  the  applica- 
tion of  the  principles  of  thermochemistry. 

As  gunpowder  is  a  mechanical  mixture,  it  is  necessary,  in 
order  to  secure  uniformity  in  the  product,  that  the  several 
ingredients  should  be  pure,  finely  divided,  and  intimately 
mixed.  We  shall  consider  first  the  preparation  of  the  in- 
gredients and  then  the  manufacture  of  the  powder. 

Refining  Saltpetre. — Refining  saltpetre  is  for  the  purpose 

of  removing  the  impurities  and  all  earthy  matter  which  may 

be    present,    and   is    effected    by   boiling   and   skimming  the 

grough    or  crude  saltpetre  in 'large   open   boilers,    and   after- 

*  wards  drawing  off  the  liquor  and   filtering  it  through  canvas 

J  bags.      The  modus  operandi  is  as  follows :      About  2   tons  of 

saltpetre  in  its  crude  state  are  put  into  an  open  copper  boiler 

capable  of  containing  500  gallons;  about  270  gallons  of  water 

are  added  to  this,   or  about  .66  of  water  to    I   of  saltpetre; 


CLASSIFICATION   OF  EXPLOSIVE   MIXTURE'S.  67 

these  are  allowed  to  stand  all  night ;  in  the  morning  a  fire  is 
lighted  under  the  boiler,  and  in  about  two  hours  afterwards 
they  will  have  reached  a  temperature  of  300°  Fahr.  and  will 
be  boiling  freely. 

During  ebullition  by  constant  stirring,  the  light  matter, 
containing  many  impurities,  rises  to  the  surface  and  is 
skimmed  off  (a  little  dissolved  glue  will  facilitate  the  opera- 
tion). When  the  scum  ceases  to  rise,  cold  water  is  freely 
dashed  on  the  surface  of  the  boiling  liquid  to  precipitate  the 
chlorides  that  would  otherwise  be  retained  on  its  surface. 
After  boiling  until  the  solution  of  the  nitrous  salts  is  effected, 
the  fire  is  allowed  to  go  out ;  when  all  ebullition  has  ceased, 
the  foreign  salts  and  chlorides,  being  the  heaviest,  are  precipi- 
tated. The  boiler  is  provided  with  a  false  bottom  perforated 
with  holes,  through  which  these  impurities  pass  and  fall  to 
the  bottom  of  the  boiler. 

In  about  an  hour  after  the  fire  has  been  extinguished,  the 
temperature  of  the  solution  falls  to  about  220°  Fahr.  A 
.siphon  is  introduced,  the  end  of  which  is  kept  about  I  inch 
from  the  false  bottom  of  the  boiler,  so  as  not  to  disturb  the 
sediment.  The  liquor  is  drawn  off  by  the  siphon  into  a 
trough,  the  bottom  of  which  is  fitted  with  four  or  five  gun- 
metal  taps  communicating  with  suspended  Dowlas  canvas 
filtering-bags,  of  the  shape  cf  an  inverted  cone.  If  crystals 
form  on  the  filtering-bags,  hot  water  is  poured  over  them  to 
keep  the  canvas  open,  a  constant  supply  for  the  purpose  being 
obtained  from  a  vessel  provided  with  a  flexible  pipe,  having  a 
finely  pierced  rose-head,  placed  in  close  proximity  to  the 
filtering-trough.  When  all  the  liquor  has  passed  through  the 
filtering-bags,  it  is  run  to  a  cooler  about  12  feet  long  by  6 
feet  wide  by  I  foot  deep,  lined  with  sheet  copper,  and  placed 
by  the  side  of  a  washing-vat. 

The  liquor  in  the  cooler  is  stirred  by  a  wooden  rake  until 
the  temperature  is  reduced  to  about  180°  Fahr.,  at  which 
temperature  the  mother-water  separates  from  the  saltpetre 
held  in  solution;  when  it  falls  below  180°  a  large  number  of 
very  minute  crystals  are  formed,  which  are  collected  and 


68  LECTURES   ON  EXPLOSIVES. 

thrown  on  to  a  wire-cloth  drainer,  fixed  at  an  angle  immedi- 
ately above  the  cooler,  that  the  strainings  may  run  back  again 
into  the  cooler;  the  'saltpetre,  when  sufficiently  drained,  is 
raked  into  the  washing-vat — also  furnished  with  a  false  bot- 
tom of  fine  copper-wire  cloth. 

The  whole  charge  receives  three  washings ;  in  the  first  and 
second  pure  water  is  freely  sprinkled  over  the  saltpetre  from 
a  rose,  and  after  standing  about  fifteen  minutes  the  liquor, 
being  very  rich  in  mother-water  and  saltpetre,  is  run  off  into 
crystallizing-pans  by  a  tap  at  the  bottom  of  the  washing-vat. 
In  the  third  washing  the  vat  is  entirely  filled  with  cold  water, 
and  the  liquor,  after  standing  for  about  half  an  hour,  is  drawn 
off;  it  now  only  contains  a  small  quantity  of  saltpetre,  and  is 
not  run  into  the  crystallizing-pans,  but  collected  in  an  under- 
ground tank  for  future  use. 

The  saltpetre  obtained  by  the  above  process  is  an  almost 
perfectly  pure  white  salt.  It  is  placed  in  stone  bins  per- 
forated with  small  holes  in  the  ends  and  sides,  where  it  is 
allowed  to  drain.  The  saltpetre  contains  from  7  to  12  per 
cent  of  water,  but  during  the  time  it  remains  in  the  bins 
about  6  or  7  per  cent  is  drained  off.  It  is  now  fit  for  making 
gunpowder  if  used  immediately ;  but  if  required  for  storage  or 
transport  it  is  better  to  evaporate  the  remaining  water,  which 
is  done  by  drying  in  a  hot  chamber  in  the  following  manner: 

The  saltpetre  is  spread  out  about  two  inches  thick  on 
shallow  trays  of  sheet  copper,  and  placed  on  racks  in  a  hot 
chamber  heated  to  about  260°  Fahr.,  by  a  flue  under  the 
floor.  The  saltpetre  is  stirred  once  or  twice;  from  four  to 
six  hours  is  sufficient  to  evaporate  the  remaining  moisture. 
It  is  taken  out  and  emptied  into  shallow  trays,  allowed  to 
cool,  and  then  put  into  barrels  and  stored. 

By  the  above  process  about  three  fourths  of  the  saltpetre 
is  crystallized,  the  remaining  portion  being  held  in  solution 
by  the  mother-water  that  remains.  When  this  has  cooled  to 
within  7°  or  8°  of  the  temperature  of  the  atmosphere  large 
crystals  are  formed,  adhering  to  the  sides  and  bottom  of  the 
cooler,  and  are  collected  and  put  with  the  grough  into  the 


CLASSIFICATION  OF  EXPLOSIVE   MIXTURES.  69 

next  charge  of  the  boiler;  the  mother-liquor  is  collected  and 
pumped  into  a  boiler  and  evaporated  to  a  fourth  of  its  original 
quantity,  and  drawn  off  by  a  siphon,  passed  through  filtering- 
bags,  and  collected  in  a  receiver,  whence  it  is  run  into  copper 
pans  of  thirty-six  gallons  each  and  crystallized.  The  crystals 
obtained  in  this  manner  are  pure,  but  contain  cavities  of 
mother-water;  it  is  found  best  to  use  them  in  the  next 
charge  as  grough. 

Over  the  sediment  in  the  bottom  of  the  evaporating-pan 
hot  water  is  poured,  and  the  whole  well  stirred  to  extract  any 
saltpetre  that  may  remain ;  after  settling,  the  solution  is 
drawn  off  and  passed  through  the  filtering-bags  previous  to 
being  run  into  the  crystallizing-pans.  Should  the  filtering- 
bags  become  clogged  by  impurities  they  are  removed  and 
placed  in  larger  bags  in  a  cleaning  apparatus,  where,  together 
with  the  bags  in  which  the  saltpetre  is  imported,  they  are 
well  washed  in  hot  water;  this  water,  containing  a  small  per- 
centage of  nitre,  is  also  collected  in  the  mother-liquor  tank. 
The  bag-cleanser  is  also  used  for  washing  the  skimmings  and 
foreign  salts,  etc. ;  the  residue  with  the  refuse  from  the  evapo- 
rating-pans  is  sold  for  manure. 

The  water  from  the  various  washings  and  drainings  is  con- 
veyed to  the  underground  tank,  pumped  into  the  copper 
boiler,  and  is  used  instead  of  pure  water  in  the  next  charge ; 
as  it  contains  a  small  percentage  of  saltpetre,  a  less  quantity 
of  grough  is  required. 

Sulphur. — Is  unfit  for  use  in  a  crude  state ;  it  requires  to 
be  refined.  This  is  done  by  subliming  and  distilling. 
\/  By  melting,  all  earthy  matters  are  left  at  the  bottom  of 
the  retort  in  which  the  melting  is  done,  the  pure  sulphur  as 
vapor  passes  upward,  and  is  sublimed  and  distilled  by  con- 
densation at  two  distinct  periods  of  its  temperature. 

A  thick,  large,  round  cast-iron  melting-pot  or  retort  is 
used,  built  in  brickwork  with  a  furnace  below.  The  retort 
has  a  movable  lid,  the  joint  being  made  air-tight  by  clay ;  the 
lid  is  sufficiently  large  to  admit  a  man  for  cleaning  out  the 
pot.  In  the  lid  is  fitted  a  4-inch  plug,  tapered  for  the  purpose 


7O  LECTURES   ON  EXPLOSIVES. 

of  charging  the  retort.  Near  the  top  of  the  retort  two  pipes 
branch  at  right  angles,  each  fitted  with  a  sluice-valve  at  the 
end  nearest  the  retort ;  one  of  these,  the  subliming-pipe, 
from  12"  to  14"  in  diameter,  rising  at  an  elevation  of  35°,  is 
used  to  conduct  the  vapor  from  the  retort  to  the  subliming- 
chamber  situated  at  a  distance  of  about  15  feet  from  the  retort. 
The  chamber  is  12  feet  in  height  by  10  feet  in  diameter  at  the 
base,  dome-shaped,  lined  with  flagstones,  and  the  floor  cov- 
ered with  sheet  lead.  Near  the  bottom  are  two  doors,  the 
inner  of  iron,  the  outer  of  wood,  air-tight,  and  lined  with 
sheet-lead.  Through  the  bottom  of  these  doors  is  a  small 
tube  leading  to  a  cistern  of  water,  which  takes  up  the  sulphuric 
acid.  The  outer  pipe,  from  7  to  8  inches  in  diameter  and  8 
feet  long,  is  used  in  conveying  off  the  vapor  at  a  higher  tem- 
perature than  required  for  subliming;  this  inclines  downward 
at  an  angle  of  20°,  delivering  the  vapor  into  a  receiving-tank 
inclosed  in  an  outer  jacket ;  cold  water  from  a  cistern  circu- 
lates through  them,  through  an  annular  space  about  1.05 
inches  in  width.  The  water  enters  the  jackets  at  their  lowest 
points,  and  passes  off  at  their  highest,  near  the  retort. 

The  receiving-tank,  fitted  with  a  movable  lid  somewhat 
similarly  arranged  to  that  of  the  retort,  has  a  plugged  hole  in  the 
centre,  through  which  a  rod  is  introduced  for  gauging  its  con- 
tents. A  small  pipe  fitted  to  the  top  of  this  tank  conducts 
any  non-condensed  vapor  to  a  chamber  where  the  "  flowers" 
are  precipitated.  This  chamber  is  occasionally  cleaned  out  by 
a  small  door.  A  discharge-valve  is  fixed  to  the  bottom  of 
the  receiving-tank  for  drawing  off  the  sulphur  into  moulds. 

About  6\  cwts.  of  crude  sulphur  are  put  into  the  retort, 
the  sluice-valve  on  the  subliming-pipe  and  the  plug  in  the 
retort-lid  left  open,  the  sluice-valve  on  the  distilling-pipe 
closed,  and  a  slow  fire  applied  under  the  retort;  in  two  or 
three  hours  the  raw  material  is  melted  down. 

At  170°  Fahr.  evaporation  commences,  at  about  200° 
Fahr.  melting  begins,  239°  Fahr.  the  sulphur  is  perfectly 
fluid,  and  at  560  Fahr.  it  is  ready  for  distillation.  So  soon 
as  the  melting  begins  a  pale-yellow  vapor  arises ;  the  plug  is 


CLASSIFICATION  OF  EXPLOSIVE   MIXTURES.  Jl 

inserted  in  the  lid  of  the  retort,  the  vapor  passes  to  the  dome 
of  the  subliming-chamber  near  the  top,  and  falls  in  a  shower 
of  very  fine  condensed  particles  termed  "  flowers  of  sulphur." 

After  two  or  three  hours,  as  the  heat  increases,  the  vapor 
in  the  retort  becomes  a  deep  reddish-brown  color,  when  the 
sluice-valve  on  the  subliming-pipe  is  closed  and  that  on  the 
pipe  leading  to  the  distilling-tank  opened,  the  cold  water 
constantly  circulating  through  the  jacket  of  this  pipe  and  also 
of  the  receiving-tank  keeps  it  cool,  the  vapor  rises  from  the 
retort  and  passes  along  the  pipe,  becomes  condensed,  and 
runs  into  the  tank  below,  a  thick  yellow  fluid.  When  nearly 
all  is  distilled  (which  is  ascertained  by  gauging  the  depth  of 
the  liquid  sulphur  in  the  tank)  the  sluice-valve  on  the  dis- 
tilling-pipe  is  shut,  the  fluid  in  the  receiving-tank  allowed  to 
cool  for  an  hour  or  two,  when  it  is  run  off  by  the  valve  to 
moulds,  and  allowed  to  cool  and  solidify.  These  moulds  are 
used  wet,  otherwise  the  sulphur  will  adhere  on  solidifying. 
When  cool,  the  refined  sulphur,  broken  into  lumps,  is  ready 
for  use.  The  vapor  remaining  in  the  retorts  passes  into  the 
dome  of  the  subliming-chamber,  where  it  is  evaporated  as 
"flowers."  The  earthy  matter  in  the  retort  is  afterward 
cleaned  out. 

^  The  "  flowers  "  of  sulphur  are  unfit  for  making  gunpowder 
on  account  of  the  acid  they  contain,  crystalline  or  distilled 
sulphur  only  being  used  in  making  gunpowder.  / 

Charcoal. — Charcoal,  the  residue  after  wood  has  been 
charred,  as  an  ingredient  of  gunpowder  is  next  in  importance 
to  saltpetre.  When  uniformity  in  quality  of  gunpowder  is 
required,  great  care  must  be  exercised  in  its  preparation,  for 
the  chemical  composition  of  charcoal — i.e.,  the  percentage 
carbon  contained  therein — will  affect  the  quality  of  the  gun- 
powder to  a  considerable  degree ;  therefore  extreme  care  has 
to  be  exercised  in  charring  the  wood.  Gunpowder  should 
contain  not  less  than  1 5  per  cent  of  charcoal. 

Much  depends  upon  the  quality  and  condition  of  the 
wood  employed.  The  sap  should  be  thoroughly  dried  in  the 
wood  to  secure  the  best  quality  of  charcoal:  this  end  is  at- 


72  LECTURES   ON  EXPLOSIVES. 

tained  by  desiccating  newly-cut  timber  in  a  hot  chamber  for 
ten  or  twelve  days,  although  it  is  questionable  if  the  charcoal 
so  obtained  is  as  good  as  that  produced  from  wood  that  has 
been  seasoned  for  a  number  of  years.  Small  wood,  perfectly 
clean,  free  from  bark,  quite  dry,  are  essential  requisites  for 
making  good  charcoal. 

The  kind  of  wood  commonly  used  is  that  of  the  willow 
species — the  common  white  Dutch  willow,  the  poplar,  and 
the  alder  are  generally  preferred.  Other  woods  are,  however, 
frequently  used  ;  and  for  a  first-class  strong  powder  black  dog- 
wood is  said  to  be  best,  but  its  cost  prevents  its  being  largely 
adopted,  except  for  military  powders. 

Distilling  the  wood  in  retorts  is  the  method  usually  em- 
ployed for  procuring  a  light  and  equal  quality  of  charcoal. 
The  method  of  distilling  in  retorts  is  as  follows:  A  number 
of  retorts  are  set  in  brickwork  at  a  suitable  height  from  the 
ground  floor,  under  which  a  furnace  is  provided ;  the  bottoms 
of  the  retorts  are  protected  from  the  direct  and  intense  heat 
of  the  furnace  by  a  fire-brick  lining,  through  openings  in 
which,  and  by  flues,  the  flame  passes  round  the  retorts  before 
reaching  the  chimney,  The  wood  must  be  small,  of  eight  or 
nine  years'  growth;  it  is  obtained  early  in  the  fall,  its  bark 
entirely  removed,  cut  into  lengths  of  about  6  inches,  and 
stacked  for  drying.  When  thoroughly  dried  it  is  put  into  a 
sheet-iron  cylinder  or  "skip,"  having  a  movable  lid  or  door 
at  one  end,  which  is  placed  horizontally  on  an  iron  carnage 
corresponding  in  height  with  the  door  of  the  retort ;  the  car- 
riage is  run  forward  to  the  mouth  of  the  retort,  the  cylinder 

O       »  w 

containing  the  wood  slid  into  the  retort,  which  is  fitted  with 
an  air-tight  door,  and  which  has  previously  been  heated  to  a 
dull-red  heat. 

The  process  of  charring  commences,  the  steam,  tar,  and 
gas  in  the  wood  pass  from  the  cylinder  by  holes  in  the  door, 
through  a  pipe  to  the  furnace,  and  are  consumed.  From 
three  to  four  hours  are  required  to  completely  char  a  cylinder 
of  wood.  The  cylinder  with  its  contents  is  drawn  out  of  the 
retort  by  a  block  and  tackle,  lowered  into  an  air-tight  cooler 


CLASSIFICATION  OF  EXPLOSIVE   MIXTURES.  73 

\vith  a  close-fitting  lid,  and  allowed  to  remain  for  about  half  a 
•day ;  it  is  then  placed  in  a  smaller  cooler,  where  it  remains 
until  cold.  After  the  charcoal  has  been  carefully  picked,  it  is 
fit  for  use  in  making  gunpowder.  About  three  charges  can  be 
burned  in  each  retort  every  twelve  hours. 

A  good  and  uniformly  pure  charcoal  has,  if  properly  made, 
a  jet-black  appearance;  the  fractures  show  a  velvet-like  sur- 
face, and  appear  the  same  in  both  large  and  small  pieces.  It 
should  not  scratch  soft  polished  metal,  and  if  treated  with 
distilled  water  there  should  be  no  appearance  of  alkali. 

From  20  to  2 5  per  cent  of  charcoal  is  obtained  from  willow 
and  alder,  and  from  25  to  30  per  cent  from  black  dogwood; 
the  latter  is  very  dense,  tough,  and  of  slow  growth,  its  usual 
size  being  about  one  inch  in  thickness.  When  charred,  it 
has  a  yellowish-looking  surface,  and  is  slightly  metallic  in 
appearance. 

The  kind  of  wood  from  which  the  charcoal  has  been  made 
is  known  by  the  pith :  that  of  dogwood  is  circular,  and  large 
for  the  size  of  the  wood ;  that  of  the  willow  is  also  circular, 
but  somewhat  smaller ;  that  of  alder  forms  a  figure  of  three 
equidistant  radial  lines. 

Charcoal  is  very  porous  and  quickly  absorbs  moisture ; 
therefore  a  great  store  is  never  kept.  Previous  to  use  it  is 
very  carefully  examined  and  picked,  uncharred  pieces  being 
excluded. 

To  test  charcoal  for  an  alkali,  finely  powder  a  small  quan- 
tity and  boil  it  in  distilled  water,  filter,  and  test  with  litmus- 
paper  reddened  by  weak  acid.  Should  the  charcoal  contain 
alkali,  the  paper  will  be  partially  or  wholly  restored  to  its 
color. 

x  Pit-burned  charcoal  is  used  in  the  manufacture  of  "  pit 
gunpowder,"  and  is  suitable  for  filling  fuses,  port-fires,  etc.  ; 
it  is  also  used  for  pyrotechnic  compositions  and  such  purposes. 

Charcoal-grinding  Mill.  —  Before  the  ingredients  are 
mixed  together  they  must  be  pulverized  or  ground  to  a  fine 
powder.  Charcoal  after  standing  a  fortnight  is  ground  in  an 
apparatus  somewhat  similar  to  a  coffee-mill  on  a  large  scale. 


74  LECTURES   ON  EXPLOSIVES. 

The  mill  consists  of  a  cone  secured  on  a  vertical  spindle  pro- 
vided with  teeth  running  spirally  over  its  entire  outer  surface ; 
the  cone  revolves  in  a  cylinder  provided  with  teeth  on  its  inner 
surface ;  these  teeth  are  spiral  also,  but  incline  in  the  opposite 
direction  to  those  on  the  cone. 

The  revolving  cone  is  adjustable  in  a  vertical  direction  to 
increase  or  diminish  the  space  between  its  teeth  and  those  of 
the  fixed  cylinder;  thus  a  coarse  or  fine  charcoal  is  produced 
at  will.  The  adjustment  is  effected  by  means  of  two  hand- 
wheels  working  on  a  fine  screw-thread  cut  upon  the  small  ver- 
tical cone  spindle,  which  spindle  can  be  moved  upward  or 
downward  by  means  of  the  hand-wheels  through  the  large 
hollow  shaft  upon  which  the  bevel  driving-wheel  is  keyed. 
Motion  is  communicated  from  this  shaft  to  the  small  one  by 
means  of  a  feather  -upon  the  surface  of  the  latter,  which  fits, 
and  works  in  a  groove  cut  in  the  jnside  of  the  hollow  shaft. 
The  small  hand-wheel  is  used  for  locking  and  securing  the 
larger  one  in  any  required  position. 

The  hopper  above  receives  the  charcoal.  On  the  under 
side  of  the  cone,  and  revolving  with  it,  are  a  couple  of  arms 
that  carry  the  ground  charcoal  to  the  discharge-spout  on  one 
side  of  the  fixed  cylinder  and  conduct  it  to  a  sifting-reel ;  this 
reel  is  simply  a  skeleton  cylinder  of  wood  covered  with  copper- 
wire  cloth  having  fine  meshes — thirty-two  to  the  inch. 

The  sifting-reel  is  driven  by  a  pair  of  bevel-wheels  set  at 
a  slight  angle  to  allow  the  charcoal  to  run  readily  along  the 
interior ;  as  it  revolves  it  causes  the  particles  of  charcoal  to 
be  continually  rolling  over  each  other  and  covering  new  sur- 
faces of  the  reel;  the  fine  particles  pass  through  the  meshes 
of  the  wire-cloth  and  fall  into  a  receiving-bin,  whilst  the 
larger  ones  are  thrown  out  at  the  lower  end  of  the  reel  to 
another  bin,  whence  they  are  taken  and  returned  to  the 
hopper.  The  reel  and  bins  are  inclosed  entirely  in  a  wooden 
framework  and  covering,  so  as  to  prevent  the  dust,  which  is 
very  light,  from  spreading  over  the  house.  Doors  are  pro- 
vided in  this  wooden  covering  by  means  of  which  the  ground 
charcoal  can  be  removed. 


CLASSIFICATION  OF  EXPLOSIVE   MIXTURES.  75 

After  being  ground,  the  charcoal  stands  for  about  eight 
or  ten  days  before  using  it;  owing  to  the  readiness  with 
which  it  absorbs  oxygen  when  in  the  pulverized  state,  it  is 
apt  to  become  heated  and  spontaneous  combustion  to  ensue. 
The  danger  from  this  cause  is  much  lessened  when  it  is 
stored  in  small  quantities  and  in  separate  iron  cylinders 
or  bins. 

Saltpetre  and  Sulphur  Grinding  Apparatus. — The  salt- 
petre, if  used  immediately  after  being  purified,  is  so  fine  as  to 
require  no  further  reduction  of  its  particles  before  mixing; 
but  if  it  has  been  dried  for  storage  it  must,  like  the  sulphur, 
be  reduced  to  a  very  fine  powder.  They  are  ground  sepa- 
rately in  a  small  machine  somewhat  similar  to  a  mortar-mill. 
The  machine  consists  of  a  pair  of  edge-rollers  travelling 
round  a  strong  circular  cast-iron  bed,  revolving  at  the  same 
time  on  their  own  axis. 

The  speed  of  these  rollers  is  eight  revolutions  per  minute 
round  the  bed ;  they  are  each  4  feet  in  diameter,  and  weigh 
30  cwt.  Each  one  travels  on  a  different  path,  one  being  near 
to  the  inside  curb,  or  "cheese,"  as  it  is  technically  called, 
whilst  the  other  is  farther  away  from  the  centre.  A  shaft  or 
spindle  common  to  both  passes  through  their  centres,  and 
between  them  is  a  cross-head  fixed  on  a  vertical  shaft  driven 
by  means  of  bevel-gearing,  the  pinion  being  secured  on  the 
main  horizontal  driving-shaft  underneath  the  machine,  whilst 
the  vertical  shaft,  upon  which  the  large  bevel-wheel  is  fixed, 
passes  through  the  cross-head ;  this  latter  being  provided  with 
suitable  brass  bushes  in  order  to  allow  the  rollers  to  rise  or 
fall  according  to  the  thickness  of  the  material  under  them. 

The  material  to  be  ground,  whether  saltpetre  or  sulphur, 
is  spread  evenly  over  the  bed  of  the  machine  to  a  thickness 
of  about  1.50  or  2  inches;  the  rollers  are  then  set  in  motion. 
A  very  short  time  suffices  to  complete  the  operation.  The 
material,  when  ground,  is  shovelled  from  the  bed  into  tubs 
and  emptied  into  a  hopper  placed  above  a  sifting-reel  which 
is  similar  in  all  respects  to  the  charcoal  reel.  As  the  reel 
revolves,  certain  projections  provided  on  the  shaft  strike 


?  LECTURES   ON  EXPLOSIVES. 

against  similar  projections  on  the  bottom  of  the  trough  that 
conveys  the  material  from  the  hopper  to  the  reel,  and  as  this 
trough  is  slung  under  the  hopper  it  is  made  to  vibrate  and 
cause  the  material  to  be  shaken  gradually  from  the  hopper  to 
the  reel.  The  fine  particles  pass  through  a  wire  cloth  of 
thirty-two  meshes  to  the  inch  and  fall  into  a  bin  provided ; 
the  coarse  particles  are  thrown  out  at  the  end  into  another 
bin,  whence  they  are  taken  and  reground. 

The  ingredients  are  now  ready  for  the  manufacture  of  the 
powder. 

Manufacture  of  Gunpowder. — The  manufacture  of  gun- 
powder consists  of  the  following  processes:  (i)  mixing  the  in- 
gredients; (2)  incorporating,  or  "milling";  (3)  breaking 
down  the  mill-cake;  (4)  pressing;  (5)  granulating,  or  cutting 
the  press-cake;  (6)  dusting;  (7)  glazing;  (8)  second  dusting: 
(9)  stoving,  or  drying;  (10)  finishing. 

Mixing  the  Ingredients. — The  ingredients  are  carefully 
weighed  out  in  the  proper  proportions  for  a  5<D-pound  mill- 
charge,  with  an  extra  amount  of  saltpetre  according  to  the 
moisture  found  to  be  contained  in  it ;  they  are  then  placed 
in  the  mixing-machine,  which  consists  of  a  cylindrical  gun- 
metal  or  copper  drum,  with  an  axle  passing  through  its  centre, 
upon  which  are  disposed  several  rows  of  gun -metal  fork-shaped 
arms,  called  "flyers."  When  in  operation,  the  drum  anc 
"flyers"  revolve  in  opposite  directions  and  at  different  rates 
of  speed. 

After  being  mixed  in  this  machine  for  about  five  minutes, 
the  composition  is  passed  through  a  hand-sieve  over  a  hopper, 
falls  into  a,  bag  placed  below,  and  is  tied  up  ready  for  the 
incorporating  mill.  It  is  now  called  a  "  green  "  charge. 

Incorporating  or  Milling. — The  incorporating-mill  consists 
of  a  circular  iron  bed,  about  7  feet  in  diameter,  firmly  fixed, 
upon  which  revolves  a  pair  of  cast-iron  cylindrical  edge-runners, 
the  edges  of  which  are  now  usually  surface-chilled.  The 
diameter  of  the  runners  is  about  6  feet,  and  their  width  15 
inches ;  they  have  a  common  axle  which  rests  in  gun-metal 
bouches  in  a  solid  cross-head  attached  to  a  vertical  shaft. 


CLASSIFICATION  OF  EXPLOSIVE  MIXTURES.  77 

The  shaft  passes  through  a  bearing  in  the  centre  of  the  bed, 
and  by  a  system  of  gearing  is  driven  by  machinery  which,  in 
the  latest  steam-mills,  is  placed  beneath  the  bed  in  cast-iron 
tanks.  Each  runner  weighs  about  4  tons,  and  travels  with 
the  average  speed  of  about  8  revolutions  per  minute.  The 
bed  has  a  sloping  rim  on  the  outside  called  the  curb,  and  on 
the  inside  an  edge  formed  by  the  "cheese,"  or  bearing 
through  which  the  shaft  passes.  The  runners  are  not  equi- 
distant from  the  centre  of  the  bed,  one  working  the  part  of 
the  charge  near  the  centre,  the  other  the  outer  portion ;  their 
paths,  however,  overlap.  Two  wooden  leather-shod  "  ploughs" 
attached  by  means  of  arms  to  the  cross-head,  one  working 
next  to  the  shaft  and  the  other  close  to  the  curb,  throw  the 
composition  under  the  runners. 

The  charge  is  spread  evenly  over  the  bed  with  a  wooden 
rake,  and  contains  about  2  pints  of  water;  additional  water 
(from  2  to  6  pints)  is  added  from  time  to  time,  according  to 
the  state  of  the  atmosphere.  This  is  done  for  the  threefold 
purpose  of  preventing  powder-dust  from  flying  about,  facili- 
tating the  incorporation,  and  reducing  the  effect  of  an  explo- 
sion in  case  of  an  accident. 

During  the  process  of  incorporation  a  millman  enters  the 
mill  occasionally,  takes  a  wooden  "shover,"  and  pushes  the 
outside  of  the  charge  into  the  middle  of  the  path  of  the  run- 
ners, to  insure  uni-form  incorporation  of  the  entire  charge. 
The  action  of  the  runners  is  a  combination  of  rolling  and 
twisting,  and  has,  on  a  large  scale,  somewhat  the  effect  of  a 
pestle  and  mortar,  crushing,  rubbing,  and  mixing  the  ingre- 
dients, thereby  effecting  an  intimate  union. 

The    time    of    milling    depends   upon    the   nature   of  the 
powder.      For  good  fine-grained  powders  it  varies  from  4  to 
8  hours;    the  very  best   sporting  powders   require    12   hours 
under  the  runners;   blasting  and  cannon  powders  are  incorpo 
rated  from  2  to  4  hours. 

This  process  demands  the  utmost  care  and  attention  and 
should  be  conducted  by  experienced  men,  as  the  quality  of 
the  powder  depends  entirely  upon  this  operation,  and  no 


78  LECTURES   ON  EXPLOSIVES. 

subsequent  treatment  can  remedy  imperfect  or  defective 
incorporation. 

When  the  ingredients  have  become  incorporated  the 
product  is  known  as  "mill-cake,"  and  it  should  be  homo- 
geneous in  appearance,  without  any  visible  specks  of  sulphur 
or  saltpetre,  and  of  a  dark  grayish  or  brownish  color,  accord- 
ing to  the  charcoal  used. 

The  mill-cake  is  carefully  tested  to  ascertain  whether  it 
contains  the  proper  amount  of  moisture.  This  should  be 
from  2  to  3  per  cent  for  fine-grained  powders,  and  from  3  to 
5  per  cent  for  powders  of  larger  granulation. 

There  is  greater  danger  of  an  explosion  during  the  incor- 
poration than  in  any  process  of  manufacture.  The  millmen 
only  enter  the  mill  occasionally  to  "liquor, "or  shift  the 
charge  on  the  bed.  The  building  itself  is  made  as  light  as 
possible,  the  roof,  and  front,  and  rear  sides  being  constructed 
of  very  light  boards,  or  even  of  canvas  on  wooden  frames, 
while  the  partitions  between  each  pair  of  rollers  are  of  solid 
masonry  or  heavy  brickwork.  Directly  over  the  bed  of  each 
mill  is  a  flat  lever-board,  or  "  shutter,"  in  gear  with  a  tank 
of  water,  so  arranged  that  when  the  shutter  is  raised  on  its 
pivot  by  an  explosion,  the  water  is  upset  into  the  bed ;  a 
horizontal  shaft  connects  all  the  shutters  in  a  group  of  mills, 
so  that  the  explosion  of  one  mill  at  once  drowns  all  the  re- 
maining charges.  The  tanks  can  also  be  overturned  by  hand. 

Breaking  down  the  Mill-cake. — After  removal  from  the 
incorporating-mill,  the  mill-cake  is  broken  down,  or  reduced 
to  powder-meal,  so  that  it  can  be  loaded  into  the  press-box. 

The  breaking-down  machine  consists  essentially  of  two 
pairs  of  gun-metal  rollers,  set  in  a  strong  frame  of  the  same 
material ;  one  roller  in  each  pair  works  in  sliding  bearings 
connected  with  a  weighted  lever,  so  that  a  hard  substance  can 
pass  through  without  any  dangerous  friction.  An  endless 
canvas  band,  with  transverse  leather  strips  attached,  conveys 
the  pieces  of  mill-cake  from  a  hopper  to  the  top  of  the  ma- 
chine, where  it  falls  between  the  first  pair  of  rollers ;  after 
passing  through  the  second  pair  of  rollers,  which  are  directly 


CLASSIFICATION  OF  EXPLOSIVE   MIXTURES.  79 

below  the  first,  the  meal  falls  into  wooden  boxes,  which  are 
placed  upon  carriages,  and  conveyed  to  small  magazines, 
whence  it  is  taken  to  the  press. 

Pressing. — The  last  operation  and  that  of  pressing  the  meal 
into  a  solid  cake  is  for  the  purpose  of  fitting  it  to  be  made 
into  a  hard  grain  of  uniform  density. 

The  powder  is  brought  from  the  small  magazines  to  the 
press-house,  where  it  is  compressed  into  hard  slabs,  or  sheets. 

The  press-box  is  usually  of  oak,  with  a  strong  gun-metal 
frame,  and  so  constructed  that  three  of  the  sides  can  turn 
back  on  hinges,  or  be  screwed  firmly  together.  To  introduce 
a  charge  of  powder-meal  into  the  box,  it  is  laid  sidewise,  the 
top  being  temporarily  closed  by  a  board,  and  the  uppermost 
side  alone  being  open,  and  gun-metal  plates  are  placed  verti- 
cally in  the  bore,  being  separated  by  narrow  strips  of  wood,  or 
racks,  the  distance  between  the  plates  being  regulated  by  the 
particular  kind  of  gunpowder  required  in  the  final  product. 

The  meal  is  poured  between  the  plates  and  rammed 
evenly,  and  the  racks  are  then  withdrawn. 

The  remaining  or  upper  side  of  the  box  is  screwed  on, 
and  the  box  is  turned  up  into  a  vertical  position,  and  placed 
on  the  table  of  the  hydraulic  ram  directly  under  the  fixed 
press-block.  The  pumps  (which  are  in  a  separate  building) 
are  now  set  in  motion,  and  the  press-block  allowed  to  enter 
the  box.  In  the  most  improved  presses,  as  soon  as  the  block 
has  reached  the  point  to  which  it  is  desired  to  compress  the 
powder,  the  edge  of  the  block  releases  a  spring  and  rings  a 
bell  as  a  signal  to  stop  the  pumps.  The  powder  is  kept  under 
pressure  for  a  few  minutes,  after  which  the  ram  is  lowered, 
and  the  box  removed  and  unloaded. 

The  above  modr  for  regulating  the  pressure  is  found  to 
give  more  reliable  results  than  trusting  to  the  indicator-gauge 
of  the  hydraulic  press,  for  the  reason  that  the  elasticity,  or 
resistance  to  pressure,  of  the  meal  varies  with  the  amount  of 
moisture  in  it,  and  the  state  of  the  atmosphere. 

In  order  to  secure  uniform  density,  equal  quantities  of 
meal,  containing  equal  amounts  of  moisture,  must  be  pressed 


80  LECTURES   ON  EXPLOSIVES. 

into  the  same  space.  In  practice,  however,  the  moisture  in 
the  meal  will  slightly  vary,  whatever  care  be  taken  with  the 
mill-cake,  owing  to  the  varying  hygrometric  condition  of  the 
atmosphere  by  the  time  each  charge  comes  to  the  press. 

It  is  therefore  necessary  to  alter  the  exact  distance  the 
press-block  is  allowed  to  enter  the  box,  not  only  with  the 
nature  of  the  powder,  but  with  the  season  of  the  year,  and 
even  according  to  the  prevailing  state  of  the  weather. 

Several  objects  are  sought  in  pressing  the  powder-meal  as 
above  described.  First,  the  cake  when  made  into  grain  of 
the  required  size  absorbs  less  moisture  from  the  air;  secondly, 
the  lasting  qualities  of  the  powder  are  greatly  increased,  es- 
pecially if  glazed;  thirdly,  after  having  been  compressed,  the 
powder  is  less  liable  to  be  reduced  to  dust  in  transportation. 
V  Again,  by  a  more  intimate  union,  or  a  closer  juxtaposition,  of 
the  ingredients,  a  larger  volume  of  gas  is  produced,  bulk  for 
bulk,  than  would  result  from  a  soft,  light  powder. 

These  qualities  and  others  will  be  referred  to  again  in  a 
subsequent  lecture. 

Granulating.  — The  machine  used  for  granulating  the 
press-cake  is  somewhat  similar  in  construction  to  the  breaking- 
down  machine. 

It  consists  essentially  of  three  or  four  pairs  of  gun-metal 
rollers  fitted  with  pyramidal-shaped  teeth,  which  are  fixed 
obliquely  one  above  the  other  in  a  strong  framework ;  the 
sizes  of  the  teeth  vary  according  to  the  kind  of  grain  required, 
but  decrease  regularly  from  the  top  to  the  bottom  pair;  one 
roller  in  each  pair  works  in  a  sliding  bearing  with  a  counter- 
weight attached  to  prevent  undue  friction.  Each  pair  of 
rollers  is  connected  with  that  next  below  by  a  short  rectangu- 
lar screen  of  copper  wire,  while  underneath  all  the  rollers  are 
placed  two  long  wire  screens  fixed  in  a  frame  having  a  wooden 
bottom  ;  both  the  frame  and  the  short  connecting  screens  are 
attached  to  the  machine  by  strips  of  lancewood,  and  when 
in  operation  a  quick  vibratory  motion  is  given  to  all  the 
screens  by  means  of  a  polygonal  wheel  upon  the  main  frame 
working  against  a  loose  smooth  wheel  attached  to  the  screen- 


CLASSIFICATION   OF  EXPLOSIVE   MIXTURES.  8 1 

frame.  The  press-cake,  which  is  contained  in  a  large  hopper, 
is  fed  to  the  top  pair  of  rollers  by  an  endless  canvas  band,  as 
in  the  breaking-down  machine,  and,  after  passing  through 
these  rollers,  it  falls  upon  the  first  short  screen ;  all  that  is 
fine  enough  to  fall  through  is  sifted  by  the  vibratory  motion 
of  the  screens,  and  travels  down  upon  whichever  screen  has 
meshes  fine  enough  to  retain  it ;  the  pieces  too  large  to  pass 
through  the  short  upper  screen  are  carried  to  the  next  pair  of 
rollers,  and  so  on.  At  the  lower  end  of  the  long  screens  are 
placed  boxes  to  receive  the  different  sizes  of  grain ;  the 
"  chucks,"  or  pieces  too  large  for  any  grain,  are  again  passed 
through  the  machine,  while  the  dust,  which  falls  upon  the 
wooden  bottom  and  is  received  in  a  separate  box,  goes  to 
the  mills  to  be  worked  up  for  forty  minutes  as  a  dust-charge. 

In  this  machine,  as  in  the  case  of  the  breaking-down  ma- 
chine, no  iron  or  steel  is  exposed,  and  as  little  as  possible  of 
either  metal  is  used  in  their  construction,  the  side-frames, 
rollers,  wheels,  bolts,  nuts,  in  short  all  parts  except  the  shafts 
and  bed-plate,  being  made  of  gun-metal,  copper,  or  wood.  The 
floor  of  the  granulating-house  is  covered  with  soft  leather-hide, 
and  the  shafts  are  encased  in  copper  or  gun-metal. 

Dusting. — The  large-grain  powder,  as  it  comes  from  the 
granulating-machine,  is  called  "  foul  grain  "  on  account  of  the 
large  quantity  of  dust  it  contains,  and  to  remove  this  dust 
the  powder  next  passes  through  the  dusting-reels.  The  reels 
consist  of  a  cylindrical  framework  about  8  feet  long  and  2  feet 
in  diameter,  covered  with  a  dusting  cloth  or  canvas  of  from 
1 8  to  56  meshes  to  the  linear  inch  according  to  the  size  of 
the  grain.  The  reels  are  either  "horizontal"  or  "slope" 
according  to  the  position  in  which  they  are  fixed  or  the  object 
in  view. 

The  large-grain  powders  are  dusted  for  about  one  half 
hour  in  a  "horizontal"  reel  both  ends  of  which  are  closed; 
while  the  fine-grain  powders,  containing  a  much  greater  per- 
centage of  dust,  are  dusted  in  a  "  slope"  reel,  which  is  open 
at  both  ends,  and  revolves  on  a  shaft  fixed  at  an  angle  of  about 


82  LECTURES   ON  EXPLOSIVES. 

4°.  The  powder  is  poured  in  at  the  upper  end  of  the  reel, 
and  is  received  in  barrels  placed  at  the  lower  end. 

Glazing. — As  a  general  rule,  all  large -grained  powders  are 
glazed,  and  recently  nearly  all  fine-grained  powders  are  sub- 
jected to  the  same  process,  the  object  being  to  diminish  the 
formation  of  dust,  and  to  render  the  powder  less  hygroscopic. 

The  glazing  is  generally  conducted  in  the  same  building  as 
the  dusting,  and  the  machine  consists  of  a  wooden  barrel  sup- 
ported by  and  attached  to  a  shaft  running  through  its  centre, 
and  the  whole,  when  in  operation,  revolves  at  about  40  revo- 
lutions per  minute.  The  barrel  is  of  oak,  and  is  about  5  feet 
long  and  3^  feet  in  diameter  at  the  centre.  The  powder  is 
introduced  into  the  barrel  through  a  small  door,  and  with  it 
about  one  half-ounce  of  graphite  or  plumbago  to  100  pounds 
of  powder.  The  door  is  closed  and  the  apparatus  set  in 
motion  and  allowed  to  run  for  about  6  hours,  at  the  end  of 
which  time  a  fine  gloss  will  have  been  imparted  to  the  grains, 
and  all  sharp  angles  and  corners  rubbed  off. 

Second  Dusting. — The  operation  of  glazing  always  pro- 
duces a  small  quantity  of  dust,  which  is  removed  by  again 
passing  the  powder  through  a  "slope"  reel. 

Stoving. — All  kinds  of  gunpowder  are  dried  in  the  same 
way.  The  *'  stove"  or  drying  -  room  is  fitted  with  open 
framework  shelves  or  racks,  the  heat  being  supplied  by 
steam-pipes  beneath.  The  powder  is  spread  upon  either 
copper  trays  or  wooden  frames  with  canvas  bottoms  (each 
having  a  capacity  of  about  12  pounds),  which  are  then  placed 
upon  the  racks.  The  length  of  time  required  for  stoving 
depends  upon  the  nature  of  the  powder  and  the  proportion  of 
moisture  it  contains ;  it  varies  from  about  twelve  hours  for 
fine-grained  powders  to  three  or  four  days  for  large-grained 
cannon-powders;  the  heat  ranges  from  120°  F.  to  145°  F. 
It  is  all-important  that  the  stove  should  be  well  ventilated, 
so  that  a  constant  supply  of  hot  dry  air  may  be  supplied  and 
the  air  charged  with  vapor  carried  off;  otherwise  the  moisture 
would  be  recondensed  upon  the  powder  as  the  temperature 
was  lowered. 


CLASSIFICATION  OF  EXPLOSIVE   MIXTURES.  83 

Finishing. — The  drying  process  again  produces  a  small 
quantity  of  dust,  which  is  removed  by  running  the  powder 
for  about  three  hours  in  a  "  horizontal"  reel. 

In  addition  to  merely  removing  the  dust,  the  finishing 
process  imparts  to  the  grains  a  very  smooth,  glossy  appear- 
ance, even  when  no  graphite  has  been  used  in  the  glazing- 
barrels.  Large  -  grained  cannon  -  powders  are  finished  in 
skeleton  wooden  reels,  and  during  the  process  a  very  small 
quantity  of  the  purest  graphite  is  introduced  in  muslin  bags. 
Advantage  is  also  taken  of  this  last  step  in  the  manufacture 
of  powder  to  mix  together  charges  of  different  glazings,  so  as 
to  secure  uniform  results. 


LECTURE   V. 
GUNPOWDER — (continued.} 

Special  Powders. — For  some  years  it  has  been  a  recog- 
nized fact  that  the  ignition,  combustion,  and  explosive  effect 
of  gunpowder  depend  in  a  great  degree  on  the  size,  shape, 
and  density  of  the  grain,  and  that  guns  of  different  calibres 
require  for  their  most  efficient  service  powders  differing  in 
these  features  in  order  to  secure  the  best  results.  The  rapid 
increase  in  weight  of  projectiles  with  the  increase  in  calibre 
of  guns,  and  the  comparatively  smaller  power  of  resistance  of 
the  guns,  renders  it  necessary  that  the  rate  of  combustion  of 
the  charge  be  regulated  so  as  to  reduce  the  strains  on  the 
guns  as  much  as  possible,  while  at  the  same  time  preserving 
high  initial  velocity  to  the  projectile,  thus  rendering  practi- 
cable the  use  of  the  heaviest  guns,  projectiles,  and  charges. 

The  amount  of  gas  evolved  at  the  first  instant  of  inflam- 
mation and  combustion  may  be  measurably  controlled  by  the 
size  and  form  of  the  grains.  Thus  by  diminishing  the  sur- 
face of  ignition  and  increasing  the  density,  greater  resistance 
is  offered  to  the  penetration  of  the  heated  gases  through  the 
grains,  and  the  rate  of  inflammation  and  combustion  is  corre- 
spondingly decreased. 

The  form  of  grain  affecting  the  amount  of  surface  ex- 
posed to  combustion — that  shape  which  offers  a  compara- 
tively small  surface  at  the  first  instant  of  ignition,  increasing 
progressively — is  theoretically  the  best. 

Experiments  by  all  civilized  nations  have  settled  beyond 
cavil  the  important  part  played  by  powders  suited  in  the 

84 


GUNPOWDER.  85 

above  qualities  to  the  guns  in  which  they  are  to  be  used,  and 
have  led  to  the  adoption  of  large-grain  powders  in  heavy 
guns,  resulting  in  the  production,  among  the  best,  of  mam- 
moth, pebble,  cubical,  hexagonal,  pellet,  and  perforated  pris- 
matic poivder. 

To  General  Rodman,  Ordnance  Department,  United 
States  Army,  belongs  the  honor  of  the  first  investigation  and 
practical  results  which  led  to  the  introduction  of  the  so-called 
*' progressive  powders."  Without  changing  the  composition 
of  the  powder,  General  Rodman  clearly  demonstrated  by  his 
experiments  with  the  15 -inch  and  2O-inch  cast-iron  guns  that 
the  initial  pressures  developed  by  the  large  charges  of  powder 
necessary  for  the  service  of  guns  of  large  calibre  could  be  con- 
trolled by  merely  compressing  the  fine-grained  powder  pre- 
viously used  so  as  to  form  larger  grains  of  greater  density. 
The  first  compressed  powder  was  the  Rodmam  mammoth 
powder,  some  of  the  grains  of  which  were  three  inches  in  di- 
ameter. This  powder  was  quickly  imitated  in  the  pebble  pow- 
der, which  differed  only  in  the  size  of  grain,  the  granules 
varying  in  size  from  one-half  inch  to  one  inch,  the  density 
being  about  the  same  as  that  of  the  mammoth  variety,  1.80. 

The  principle  upon  which  the  compressed  powders  were 
made  is  as  follows :  In  a  large  charge  of  fine-grain  powder,  a 
relatively  very  large  surface  of  inflammation  is  presented  at 
the  first  instant  of  ignition,  and  the  greater  part  of  the  charge 
is  burned  with  the  production  of  a  great  volume  of  gas  before 
the  projectile  has  moved  far  from  its  original  position  in  the 
bore  of  the  gun,  and  while  the  powder-chamber  is  at  its  mini- 
mum, the  result  being  the  development  of  the  maximum 
pressure  at  the  base  of  the  bore,  which  rapidly  diminishes  as 
the  projectile  moves  down  the  bore,  thereby  allowing  the  gases 
to  expand. 

The  average  force  developed  by  the  combustion  of  such 
powders  is  small  compared  with  that  exerted  at  the  first  in- 
stant of  explosion. 

The  object  of  progressive  powders  is  to  reverse  this  order 
by  presenting  the  smallest  surface  of  inflammation  at  the  begin- 


86  LECTURES   ON  EXPLOSIVES. 

ning  so  as  to  develop  only  sufficient  gas  to  overcome  the  in- 
ertia of  the  projectile,  and  to  have  the  quantity  of  gas  increase 
regularly  as  the  projectile  moves  down  the  bore  so  as  to 
distribute  the  pressure  throughout  the  gun  and  avoid  the 
intense  local  action  developed  by  the  older  powders. 

In  the  compressed  powders  it  was  sought  to  attain  this 
result  by  the  combustion  of  the  successive  layers. 

Thus  in  the  "  Fossano,"  or  "  Progressive  Powder,"  used  in 
the  loo-ton  gun  at  Spezia,  the  press-cake  was  broken  up  into 
grains  varying  in  size  from  \  to  \  of  an  inch  in  diameter, 
mixed  with  a  certain  percentage  of  rifle  or  mortar  powder,  and 
then  subjected  to  a  second  pressing.  The  density  of  the 
first  press-cake  was  about  1.79,  which  was  reduced  by  the 
second  pressing  to  a  mean  density  of  about  1.76.  The  second 
press-cake  was  subsequently  regranulated,  each  grain  being 
about  2-J-  inches  in  length  and  breadth  by  about  if  inches  in 
thickness,  and  consisting  of  a  mixture  of  powders  having  two 
separate  specific  gravities,  or  densities. 

These  investigations  soon  led  to  the  adoption  by  military 
nations  of  some  regular  form  of  grain  for  powders  instead  of 
the  irregular  shapes  of  the  original  mammoth  and  pebble 
powders. 

Other  modifications  having  the  same  general  object  in 
view  were  introduced  from  time  to  time,  and  serve  to  distin- 
guish the  various  special  powders  now  in  use. 

Hexagonal  Powder. — The  hexagonal  powder  used  in 
guns  of  large  calibre  in  the  U.'S.  Army  is  manufactured  by 
Messrs.  E.  I.  Dupont  &  Co.  The  uniform  size  of  grain  and 
their  polyhedral  shape  insure  great  uniformity  in  position  and 
size  of  the  interstices  in  the  cartridge ;  this  insures,  with  a 
uniform  density  of  grains,  uniformity  in  density  of  loading, 
the  result  being  equal  and  low  pressures,  together  with  uni- 
form and  good  velocities. 

Manufacture  of  Hexagonal  Powder. — The  proportions 
of  the  ingredients  of  hexagonal  powder  conform  to  the  United 
States  standard,  and  up  to  the  completion  of  the  incorpora- 


G  UNPO  WDER.  87 

tion  in  the  wheel  mill,  its  manufacture  is  like  that  of  ordinary 
powder. 

Mealing. — The  mill-cake  is  revolved  in  a  cylinder  of  wire- 
woven  cloth,  with  wooden  balls,  until  it  is  mealed. 

Pressing. — The  mealed  powder  is  then  carefully  pressed 
between  horizontal  metallic  plates  or  dies.  The  powder  comes 
out  in  a  sheet  or  cake  of  polyhedral  granules  united  along 
their  edges,  the  dies  being  nearly  perfect  dodecahedrons. 

Graining. — The  press-cake  is  passed  between  rollers  armed 
with  brass  cutting  teeth  at  an  angle  of  from  60°  to  120°  to  the 
axis,  which  cut  the  cake  into  granules,  their  cross-section 
being  almost  hexagonal,  whence  the  powder  derives  its  name. 

Glazing. — The  powder  is  then  sent  to  the  glazing-mill  and 
glazed. 

Brushing. — The  powder  is  next  passed  repeatedly  through 
the  brushing-machine.  This  consists  of  a  frame  with  brushes 
revolving  near  an  inclined  plane  along  which  the  powder  passes 
by  the  motion  of  the  brushes. 

Drying. — The  brushing  ended,  the  powder  goes  to  the 
drying-house,  where  it  is  dried.  The  powder  is  now  minutely 
examined,  its  specific  gravity  taken,  and  a  count  made  of  the 
granulation ;  a  variation  of  two  granules  to  the  pound  being 
enough  to  condemn  the  powder. 

Rebr ushing  and  Redrying. — If  satisfactory,  the  powder  is 
again  passed  through  the  brushing-machine,  redried,  and  then 
receives  a  third  brushing. 

Packing. — The  powder  is  now  packed  in  barrels  and  is 
ready  for  inspection. 

Perforated  Prismatic  Powder. — The  adoption  of  this 
form  of  powder  by  some  nations,  and  production  of  suitable 
machinery  for  its  manufacture,  necessitated  the  use  of  presses 
of  peculiar  construction  to  insure  sufficient  and  uniform  den- 
sity :  the  press  to  be  so  devised  as  to  produce  uniform  size  and 
shape  of  grains,  and  allow  their  ready  withdrawal  from  the 
moulds ;  the  surfaces  such  as  to  allow  close  packing  in  a 
given  space.  These  considerations  led  to  the  adoption  ®f  a 
regular  geometrical  figure ;  the  hexagon  offers  a  good  shape 


33  LECTURES   ON  EXPLOSIVES. 

for  piling,  the  angles  being  all  sufficiently  obtuse  to  prevent 
breaking  or  spawling  at  the  edges.  Each  layer  and  the  whole 
cartridge  is  easily  made  up.  Perforations  were  found  neces- 
sary to  insure  better  and  more  uniform  control  of  combustion 
in  the  grain.  The  number  of  perforations  first  adopted  was 
seven — one  central,  the  other  six  at  equal  distances  from  the 
central  one, — although  one  perforation  in  the  centre  has  been 
found  sufficient. 

The  ingredients  for  the  manufacture  of  the  powder-base 
are  the  same  as  used  in  manufacture  of  ordinary  powder. 
The  pulverized  materials  for  220  pounds  are  placed  in  a 
wooden  drum  lined  with  sole-leather,  with  330  pounds  of 
bronze  balls,  and  subjected  to  1440  revolutions  at  the  rate  of 
8  or  10  per  minute.  The  powder  is  then  brought  to  the 
moistening-table  of  wood  surrounded  by  an  upright  edge, 
over  which  is  suspended  a  graduated  glass  measure  having  a 
copper  pipe  and  rose  at  the  bottom.  On  the  table  a  charge 
of  55  pounds  of  powder  is  spread  and  moistened  with  2f 
quarts  of  distilled  water.  It  is  then  passed  from  a  hopper  to 
an  endless  canvas  belt  20  inches  wide,  between  a  lower  paper 
and  upper  bronze  roller  weighing  2425  pounds,  making  a 
revolution  in  twelve  minutes.  The  bronze  roller  can  be 
weighted  to  exert  a  pressure  of  60,000  pounds.  The  powder 
is  then  broken  into  coarse  lumps  by  wooden  mallets  and 
granulated  to  two  sizes  of  grains :  the  first,  cannon-powder — 
used  for  manufacture  of  the  prisms — is  passed  through  a  sieve 
of  0.26  inch  diameter  of  holes. 

Manufacture  of  Perforated  Prismatic  Powder. — Ordi- 
nary grain  powder,  made  as  above,  is  of  a  specific  gravity 
of  1.5,  and  too  elastic  for  use  in  the  press.  By  reworking 
it  loses  a  part  of  its  elasticity,  and  is  then  fit  for  formation  of 
the  prisms  by  the  following  process :  The  powder-base,  as 
above,  is  moistened  with  10  per  cent  of  water,  passed  through 
the  spindle-press  with  the  prescribed  pressure,  and  granulated, 
the  grain  and  dust  being  collected  in  a  receptacle.  This  mix- 
ture of  grain  and  dust  is  dried  in  the  air  or  by  artificial  heat 
till  if  per  cent  of  the  moisture  remains.  It  is  placed  in  a  mix- 


G  UNPO  WDER.  89 

ing-drum — 220  pounds  of  powder  and  330  pounds  of  bronze 
balls — and  subjected  to  1440  revolutions,  moistened  and 
pressed  as  before,  giving  it  a  specific  gravity  of  1.675  to  l-75- 
It  is  granulated  and  separated,  the  cannon  size  again  dried  by 
air  till  6  per  cent  of  moisture  in  dry  weather  remains,  and 
placed  in  barrels  covered  with  damp  cloths  for  use. 

The  press  for  this  purpose  is  constructed  to  give  a  pressure 
of  65,000  pounds  per  square  inch.  It  consists  of  a  heavy 
casting  on  a  stone  foundation,  a  main  and  secondary  shaft,  one 
fixed  and  two  movable  cross-heads.  These  have  each  six  hexag- 
onal stamps  perforated  with  seven  holes,  which  enter  correspond- 
ing hexagonal  moulds  on  the  lower  cross-head.  Six  groups 
of  seven  needles  are  fixed  in  such  position  that  they  extend 
up  through  the  perforations  of  the  lower  stamps  throughout 
into  the  moulds  and  enter  the  perforations  of  the  upper  stamps 
as  the  latter  descend  to  press  the  powder  in  the  moulds ;  these 
form  the  perforations  in  the  prisms.  Eccentrics  and  cranks 
operating  the  cross-heads  are  timed  so  that  when  the  upper 
stamps  have  reached  the  lowest  point  of  descent  the  lower 
ones  are  moving  upward,  giving  the  extreme  pressure,  after 
which  the  upper  stamps  ascend  and  the  lower  ones  simulta- 
neously push  the  perforated  prisms  up  from  the  moulds.  The 
lower  stamps  constitute  the  bottom  of  the  moulds.  The  moulds 
are  filled  from  a  hopper  having  a  table  with  forward-and-back 
motion,  containing  six  suitable  measures  which  receive  the 
powder  from  the  hopper;  the  charging-table  moves  forward 
and  drops  the  charge  in  the  moulds ;  its  edge  carries  the  prisms 
brought  up  from  the  mould  to  an  inclined  shelf,  whence  they 
are  removed.  The  capacity  of  the  powder  measures  can  be 
regulated  as  desired.  Two  rooms  are  required  for  each  press 
— one  for  the  press,  the  other  for  the  prisms. 

Before  starting  the  press,  the  mould-needles  and  stamps 
and  all  rubbing-surfaces  ought  to  be  oiled  with  a  light,  pure 
oil  or  graphite. 

•All  surplus  lubricant  must  be  wiped  off.  The  powder  to 
be  pressed  ought  to  have  at  least  5^  per  cent  of  moisture. 
The  moist  prisms  weigh  about  620  grains  each,  and  must  not 


9°  LECTURES   ON  EXPLOSIVES. 

vary  more  than  5  grains.  The  first  two  sets  of  prisms  should 
be  rejected  because  of  excess  of  oil.  Three  men  can  work  a 
press;  a  carrier  for  every  press  is  also  required.  The  height 
and  weight  of  the  prisms  are  verified  from  time  to  time,  and 
the  powder  in  the  hopper  is  stirred  from  time  to  time.  Loose 
powder  is  brushed  away  from  the  stamps  and  top  of  the  moulds ; 
and  all  rubbing-surfaces  are  lubricated  as  often  as  once  an 
hour.  If  a  needle  breaks,  the  press  is  stopped  and  the  needle 
replaced.  On  dry  days  the  powder  loses  moisture ;  this  is 
indicated  by  increased  height  of  prisms  or  vibrations  of  the 
press,  in  which  case  it  is  moistened  with  \  per  cent  of  mois- 
ture, which  is  done  in  a  drum  by  a  fine  rose-sprinkler.  The 
prisms  pressed  by  the  press  contain  about  5  per  cent  of  mois- 
ture, and  must  be  dried  to  about  f  per  cent  by  exposure  to 
air  or  on  shelves  in  a  suitably  arranged  drying-room  ;  they 
are  then  exposed  to  a  temperature  of  120°  Fahr.  for  48  hours, 
and  are  ready  for  packing. 

The  prisms  are  packed  in  wooden  boxes  in  layers  (12  rows 
of  14,  and  ii  rows  of  9,  6  deep)  weighing  about  no  pounds 
to  the  box. 

The  prisms  are  regular  hexagons  0^.992  high  and  i" .6 
width  across  the  angles.  The  packing-boxes  are  of  inch  stuff, 
and  may  be  tin-lined.  Two  sheets  of  felt — the  smaller  at  one 
end,  the  other  on  top — keep  the  prisms  from  rubbing  against 
each  other  in  transportation. 

The  boxes  have  rope  handles,  and  are  marked  with  the 
weight,  kind,  place,  and  date  of  fabrication  of  the  powder. 

Pellet  Powder. — Pellets  are  formed  by  compressing  the 
powder  meal  into  metal  moulds.  Various  shapes  and  sizes 
were  tried:  so. ne were  flat  disks,  others  prisms;  but  the  shape 
which  found  much  favor  at  first  was  the  cylindrical  pellet  £ 
inch  in  diameter  by  ^  inch  in  length,  and  weighing  9.5  grains. 
Originally  these  were  made  by  hand,  but  it  was  soon  apparent 
that,  if  required  m  large  quantities,  machinery  would  have  to 
be  devised  for  their  production  ;  consequently  a  large  machine, 
of  somewhat  novel  description,  and  capable  of  making  400 


GUNPOWDER.  91 

pellets  at  one  time,  was  designed  by  Dr.  John  Anderson,  and 
manufactured  m  Birmingham. 

Manufacture  of  Pellet  Powder. — This  machine  is  worked 
entirely  by  means  of  hydraulic  power  derived  from  an  accu- 
mulator, which  affords  a  pressure  equal  to  1000  pounds  per 
square  inch.  The  machine  consists  of  two  hydraulic  cylin- 
ders, with  a  division  in  the  centre  of  each,  thus  in  reality 
making  four  cylinders ;  in  the  two  upper  ones  a  plain  cylin- 
drical ram  is  fitted,  which  merely  rises  and  falls  as  the  water 
is  admitted  underneath  the  ram  or  is  withdrawn.  These 
rams  are  used,  first,  for  compressing  the  pellets,  and  second, 
for  ejecting  them,  when  finished,  out  of  the  mould-plates. 
The  two  lower  divisions  are  fitted  with  piston-rams,  securely 
attached  to  cross-heads  which  are  united  together,  and  also 
connected  to  two  other  cross-heads  above  the  cylinders  by 
means  of  strong  wrought-iron  side  rods,  provided  with  col- 
lars working  between  lugs  cast  upon  the  hydraulic  presses, 
and  so  adjusted  as  to  allow  only  a  certain  limited  travel 
either  up  or  down.  The  upper  cross-heads  can  be  adjusted 
to  their  exact  positions  by  means  of  screw-threads  and  lock- 
nuts  on  the  upper  end  of  the  side  rods.  The  use  of  the  lower 
piston-rams  is  to  close  the  upper  openings  in  the  mould-plates 
by  bringing  the  top  punches,  which  are  connected  to  the 
upper  cross-heads  by  a  gun-metal  plate,  down  upon  the 
mould-plate,  and  thus  confine  the  powder  meal  in  the  moulds. 
The  upper  rams  are  now  slowly  raised,  and  these,  acting 
upon  the  lower  punches,  compress  the  powder  in  the  mould 
plate.  After  the  proper  density  has  been  secured,  the  action 
of  the  lower  rams  is  reversed,  by  which  means  both  the  lower 
and  upper  cross-heads  receive  an  upward  motion,  thereby 
raising  the  upper  punches  clear  out  of  the  way,  so  as  to 
admit  of  the  compressed  pellets  being  ejected  out  of  the 
mould-plate,  and  this  is  done  by  giving  a  further  upward 
motion  to  the  two  plain  cylindrical  rams. 

To  compress  the  powder  in  the  mould  and  form  a  pellet 
requires  four  distinct  movements  of  the  machine.  First,  the 
upper  punch  is  brought  down  until  it  rests  upon  the  mould- 


92  LECTURES   ON  EXPLOSIVES. 

plate  and  closes  the  mould ;  this  is  effected  by  a  downward 
motion  of  the  two  lower  piston-rams,  to  which  the  upper  and 
lower  cross-heads  are  connected  together  with  the  upper 
punches.  Secondly,  the  lower  punches  are  raised  by  the  two 
apper  plain  rams,  and  the  powder  is  compressed  in  the  mould 
between  the  two  punches.  Thirdly,  when  the  pellet  is  suffi- 
ciently compressed  the  upper  punches  are  raised  from  the 
mould-plate,  this  being  done  by  reversing  the  action  of  the 
two  lower  piston-rams  until  the  upper  cross-head  and  punches 
are  at  a  sufficient  height  to  admit  of  the  compressed  pellet 
being  ejected  out  of  the  mould-plate.  This  fourth  and  last 
operation  of  ejecting  the  pellet  is  effected  by  allowing  the 
upper  plain  rams  to  rise  still  further,  and  thus  force  the  fin- 
ished pellet  out  of  the  mould  by  means  of  the  lower  steel 
punches. 

It  is  seen  that  a  machine  of  this  description  is  capable  of 
making  pellets  of  almost  any  shape,  such  as  cylindrical,  hex- 
agonal, prismatic,  or — what  is  possibly  the  best  of  all — 
spherical,  by  merely  altering  the  form  of  the  mould  and 
punches.  In  the  machine  referred  to  there  are  (on  a  revolv- 
ing table,  the  framework  of  which  is  made  of  gun-metal)  four 
mould-plates  fitted ;  each  contains  200  holes,  but  as  there  are 
only  two  hydraulic  presses  to  the  machine  it  follows  that  only 
two  sets,  or  400  moulds,  are  under  compression  at  one  time; 
so  that  if  we  number  these  mould-plates  consecutively,  then 
Nos.  I  and  3  will  be  under  pressure  whilst  Nos.  2  and  4  are 
being  filled.  When  the  powder  in  Nos.  I  and  3  mould-plate 
is  sufficiently  compressed,  and  the  pellets  formed  therein  have 
been  removed,  the  entire  table  is  turned  one  fourth  of  the 
way  round  by  means  of  a  handle  and  a  toothed  pinion  work- 
ing into  corresponding  teeth  provided  round  the  periphery  of 
the  gun- metal  table.  Nos.  2  and  4  mould-plates,  which  have 
been  wholly  filled  with  meal-powder,  are  now  brought  under 
the  cross-heads  of  the  machine  and  are  in  position  for  the 
powder  contained  therein  to  be  compressed  into  pellets,  whilst 
Nos.  I  and  3  in  turn  take  their  places  to  be  refilled ;  the 
operation,  therefore,  of  pressing  and  refilling  are  continuous, 


GUNPOWDER.  93 

and  the  machine  is  capable  of  producing  a  large  quantity  of 
pebble-powder  per  day,  and  with  very  little  waste. 

Cubical  Powder. — Since  the  pellet-powder  was  first 
brought  into  use,  another  description  of  large-grain  powder, 
called  '*  pebble-powder,"  has  been  introduced  for  service 
with  guns  of  large  calibre.  The  pebble-powder  is  formed  of 
large  grains  ranging  from  eleven  sixteenths  of  an  inch  to  as 
much  as  2-inch  cubes;  to  manufacture  this  class  of  powder 
expeditiously  and  cheaply  has  brought  forth  another  descrip- 
tion of  machine  for  forming  the  pebbles  by  cutting  up  pre- 
viously compressed  cakes  into  cubes  of  the  required  dimen- 
sions. This  is  done  in  the  following  manner: 

Manufacture  of  Cubical  Powder. — The  cake  as  brought 
from  the  press-house  is  of  the  thickness  of  the  required  cubes ; 
this  cake  the  machine  has  to  cut  up — first,  into  long  strips  of 
the  same  width  as  the  thickness  of  the  cake ;  and,  secondly, 
to  cut  these  long  strips  transversely  into  cubes.  This  is 
accomplished  in  the  machine  by  means  of  two  pairs  of  rollers 
in  the  following  manner:  The  cake  is  fed  to  a  hopper  imme- 
diately above  the  first  pair  of  rollers,  provided  with  knives 
upon  their  surfaces  to  cut  the  cake  into  long  strips.  The 
strips  fall  on  an  endless  travelling  band,  which  conveys  and 
carries  them  to  the  second  pair  of  rollers,  where  they  are  cut 
transversely  into  cubes.  Then  they  drop  into  a  spout,  and 
are  delivered  to  a  revolving  sifter  covered  with  copper  wire, 
which  conveys  the  cubes  to  a  number  of  wooden  boxes  con- 
tained in  a  small  gun-metal  truck;  the  dust  and  small  pieces 
fall  through  the  sifter  into  other  boxes,  and  are  taken  back  to 
the  press-house  and  worked  up  again. 

Modifications  in  the  Manufacture  of  Gunpowder. — 
Several  processes  of  manufacture  have  been  suggested  as  sub- 
stitutes for  the  old  and  rather  slow  method  just  described,  and 
many  have  been  experimented  with,  but  except  in  cases  of 
great  emergency,  when  quantity  rather  than  quality  is  de- 
manded, the  old  methods  have  been  retained  so  far  as  to 
include  the  preparation  of  the  press-cake. 

In  the  case,  however,  of   powders  of  regular  granulation. 


94  LECTURES   ON  EXPLOSIVES. 

and  compressed  powders  generally,  the  rapid  advances  made , 
in  mechanical  devices  and  labor-saving  machines  have  greatly 
increased  the  output  of  modern  powders  over  that  of  the  older 
form   of   granulation,  which  is  at  present  limited  almost  en- 
tirely to  rifle  or  small-arm  and  blasting  powders. 

Process  followed  at  the  Augusta,  Ga.,  Mills. — In  1862 
or  1863  Col.  G.  W.  Rains  introduced  kito  the  Confederate 
Powder-mills,  Augusta,  Ga.,  a  process  of  mixing  which  was 
claimed  to  be  so  much  more  thorough  that  the  time  required 
for  incorporation  was  reduced  three  fourths. 

The  sulphur  and  charcoal  were  severally  pulverized  and 
bolted  ;  the  nitre  (pulverized  by  disturbed  crystallization)  was 
added  to  these,  and  the  mass,  roughly  mixed,  was  moistened 
with  water  and  introduced  into  horizontal  cylinders  of  sheet 
copper,  30  inches  long  by  18  inches  in  diameter.  These 
cylinders  revolved  closely  on  a  common  axis  consisting  of  a 
heavy  brass  tube  3  inches  in  diameter,  perforated  within  the 
cylinders  by  a  number  of  holes  one-eighth  inch  in  diameter. 
High  pressure  was  introduced  through  this  tube,  raising  the 
temperature  to  the  boiling-point,  while  the  water  produced  by 
condensation,  added  to  that  originally  used  to  moisten  the 
materials,  reduced  them  to  a  semi  liquid  slush,  which  was  run 
out  of  the  cylinders  after  about  eight  minutes'  rotation.  On 
cooling,  this  mud  became  a  damp,  solid  cake,  the  nitre,  which 
in  the  state  of  boiling-hot  saturated  solution  had  entered  into 
the  minutest  pores  of  the  charcoal,  now  recrystallizing.  The 
cake  so  produced  was  transferred  to  the  incorporating  mills, 
and  under  5-ton  rollers  was  in  an  hour  brought  to  the  condi- 
tion of  finished  mill-cake,  ready  to  be  cooled  and  granulated, 
while  without  the  steaming  process  four  hours'  incorporation 
in  the  mills  had  previously  been  necessary  to  produce  powder 
of  the  same  first-class  character.  The  capacity  for  work  of 
the  mills  was  thus  practically  quadrupled,  the  thorough  satu- 
ration of  the  charcoal  with  nitre  being  accomplished  by  the 
steaming,  while  it  remained  for  the  rollers  merely  to  complete 
the  mixture  of  the  whole  mass  and  give  the  required  density 
to  the  mill-cake. 


OFTHB 

UNIVERSITY 


G  UNPO  WDER>^  9  5 


Wiener  Process.  —  This  powder,  invented  by  Colonel 
Wiener  of  the  Russian  Artillery,  differs  in  its  manufacture 
from  the  ordinary  powder  in  that  all  of  the  moisture  is  elimi- 
nated in  the  press-mill,  the  mixture  here  being  brought  to  a 
temperature  of  240°  F.,  the  melting-point  of  sulphur.  In  this 
manner  equal  densities  were  obtained,  but  the  resulting 
grains  were  very  porous,  and  consequently  had  a  great  capacity 
for  moisture. 

Nordenfelt  and  Meurling  Process.  —  This  process  was 
devised  in  order  to  reduce  the  danger  attendant  upon  the 
manufacture  of  powder.  The  carbonaceous  'matter  is  first 
ground  to  a  very  fine  powder,  and  then  the  sulphur  is  pre- 
pared for  use  by  dissolving  it  in  carbon  bisulphide.  The 
solution  is  effected  by  the  aid  of  a  gentle  heat  in  a  warm  bath, 
and  the  evaporation  of  the  bisulphide  is  prevented  by  cover- 
ing it  with  a  layer  of  water. 

A  saturated  or  nearly  saturated  solution  is  thus  prepared. 
The  pulverized  carbonaceous  matter  and  the  solution  of  sul- 
phur in  CS2  are  then  thoroughly  mixed  together  in  a  closed 
vessel  containing  a  mechanical  stirrer.  When  the  mixture  is 
complete  the  solution  is  evaporated  or  distilled  off  by  the  aid 
of  a  gentle  heat.  According  to  the  inventors,  when  the  CS, 
is  evaporated  the  carbonaceous  matter  and  sulphur  remain 
intimately  mixed,  and  each  particle  of  carbonaceous  matter 
is  impregnated  with  sulphur,  instead  of  at  present.  where  the 
admixture  is  obtained  by  grinding,  the  particles  C  and  S  being 
mechanically  placed  side  by  side.  The  saltpetre  is  prepared 
for  use  by  dissolving  it  in  water;  the  solution  is  added  to  the 
pulverized  carbonaceous  matter  already  impregnated  with  sul- 
phur as  described,  and  the  whole  is  stirred  together  in  a 
mechanical  mixer. 

Modifications  in  the  Composition  of  Gunpowder.  — 
Besides  the  changes  in  the  methods  of  manufacture,  there 
have  been  several  changes  proposed  in  the  chemical  composi- 
tion, in  the  physical  condition,  and  in  both  chemical  composi- 
tion and  physical  condition  of  powders. 

The  most  notable  change  in  the  composition  of  modern 


LECTURES   ON  EXPLOSIVES. 


gunpowders  is  shown  in  the  so-called  "  Brown  Prismatic  "  or 
"  Cocoa  Powder,"  which  was  introduced  into  Germany  in 
1882. 

Brown  Prismatic  or  Cocoa  Powder. — The  exact  nature  of 
this  powder,  both  as  to  the  ingredients  themselves  and  their 
proportions,  was  for  some  time  shrouded  in  mystery,  the  name 
"Cocoa"  tending  to  this  end,  as  it  was  evidently  intended 
it  should.  There  is  now  no  doubt  that  the  peculiar  brown 
color  of  this  powder  is  due  to  the  charcoal,  which,  as  already 
stated,  is  prepared  by  carbonizing  rye  straw. 

In  1884,  Professor  Munroe,  at  that  time  Professor  of 
Chemistry  at  the  U.  S.  Naval  Academy,  analyzed  a  sample 
of  this  powder  made  at  the  Rottweil-Hamburg  Powder  Works 
at  Duneberg,  and  marked  c/82,  with  the  following  result: 

"  The  powder  was  in  the  form  of  perforated  hexagonal 
prisms,  color  of  cocoa,  of  a  hardness  of  between  2  and  3  on 
Mohr's  scale,  and  a  density  reported  as  1.86  grams.  Quali- 
tative analysis  showed  the  presence  of  potassium  nitrate,  sul- 
phur, charcoal,  and  water.  The  charcoal  was  of  a  reddish 
color,  and  behaved  towards  alkaline  hydroxides  like  under- 
burnt  charcoal.  The  action  was  specially  marked  with  am- 
monium hydroxide,  as  it  dissolved  out  a  marked  quantity  of 
humus-like  substance,  Water  also  yielded  a  marked  amount 
of  infusion. 

*  *  Quantitative  analysis  gave  •. 

I    *               II  III                  IV                Mean. 

1. 10  1. 08 

80.36  80.44 

15.99  15-9° 

2.26  £.24            2.28               2.24 


Moisture 1.05 

Nitre 80.52 

Charcoal 15.80 

Sulphur. 2.19 


The  charcoal  contained  : 


Carbon 48.43 

Hydrogen 5.58 

Oxygen 44.64 

Ash 1.35 


II 

48.17 
5.60 

44-93 
1.30 


III 

48.39 
5-53 

44-75 
1-33 


99.66 


100.00 


G  UNPO  WDER.  97 

1 '  It  is  to  be  seen  by  these  analyses  that  the  cocoa  powder 
differs  markedly  from  the  U.  S.  regulation  powder — 
"  1st.   In  the  proportions  of  the  ingredients: 

U.  S.  Regulation  Powder. 

Nitre 75-OO 

Charcoal 1 5 .00 

Sulphur 10.00 

100.00 

"  2d.  In  the  character  of  the  charcoal,  which  is  red  in- 
stead of  black. 

"  In  order  to  learn  more  of  the  nature  of  the  charcoal,  a 
partial  analysis  of  the  ash  was  made.  The  ash  was  red- 
colored.  It  yielded: 

Silica 13.93 

Ferric  oxide 2 5 .40 

Alumina 8.32 

Lime 28.50 

Magnesia 7.28 

Undetermined 16.57 

100.00 

"The  presence  of  alumina  in  the  ash  seems  to  point  to 
the  club-moss  or  some  similar  lycopodiaceous  plant  as  the 
source  of  the  charcoal." 

Properties  Peculiar  to  Cocoa  Powder. — One  noteworthy 
peculiarity  of  cocoa  powder  is  its  velocity  of  combustion,  which 
is  so  low  that  a  grain  may  be  held  in  the  hand  and  ignited, 
and  then  placed  on  the  ground  before  the  burning  portion 
reaches  the  fingers. 

With  a  single  grain  weighing  42.4384  grams,  the  time  of 
burning  was  17  seconds.  Even  when  powdered  it  burns 
much  more  slowly  than  pulverized  black  powder,  which  would 
show  that  the  slow  combustion  was  not  due  to  the  great 
density  and  hardness  only. 

The  advantage  of  the  cocoa  over  other  powders  exists  in  its 


9$  LECTURES   ON  EXPLOSIVES. 

property  of  imparting  a  high  initial  velocity  to  the  projectile, 
while  exerting  a  relatively  low  pressure  on  the  walls  of  the 
gun.  This  is  due  to  a  number  of  causes,  viz. : 

1.  The  form  of  the  grain. 

2.  The  size  of  the  grain. 

3.  The  great  density  of  the  grain. 

4.  The  great  hardness  of  the  grain. 

5.  The  small  percentage  of  sulphur. 

6.  The  easy  inflammability  of  the   charcoal   or  carbohy- 
drates. 

7.  The  relatively  great  heat  evolved. 

8.  The  simplicity  of   the  chemical  reaction  as  shown  by 
Noble. 

(5)  tends  to  reduce  the  readiness  with  which  the  powder 
will  ignite  or  raises  its  point  of  ignition,  even  when  the  grain 
is  pulverized. 

(i),  (2),  (3),  (4),  and  (5),  combined,  operate  so  long  as  the 
first  four  exist  to  produce  a  very  slow  rate  of  combustion. 
By  the  time,  however,  that  the  projectile  is  moved  from  its 
seat,  the  grains  will  be  reduced  in  size  and  more  or  less 
broken  up.  We  then  have  a  finer-grained  powder,  which  is 
highly  inflammable  at  the  temperature  which  exists,  and  con- 
sequently the  volume  of  gas  evolved  will  increase  rapidly  as 
the  volume  of  the  chamber  increases.  Owing  to  the  relatively 
great  amount  of  heat  evolved  (7),  the  cooling  effect  of  the 
envelope  is  less  marked  than  with  other  powders.  From  the 
comparatively  simple  chemical  reaction  it  is  probable  that  the 
rapidity  of  the  reaction  is  more  uniform  than  in  the  more  com- 
plex reactions  resulting  from  the  explosion  of  other  powders. 

DuPont  Brown  Powder. — In  1887  the  DuPont  Com- 
pany produced  a  brown  powder  which  equalled,  if  it  did  not 
excel,  the  powders  of  the  same  class  previously  used  abroad. 
In  his  specifications  Mr.  Eugene  DuPont  sets  forth  the 
nature  of  the  new  powder  substantially  as  follows : 

To  obtain  a  powder  possessing  great  ballistic  power,  and 
at  the  same  time  obviate,  partially  at  least,  the  disadvantages 
arising  from  the  combustion  of  the  powder  due  to  the  great 


C  UNPO  WD  ER.  99 

volume  of  smoke,  the  ordinary  charcoal  previously  used  in 
the  manufacture  of  gunpowder  is  replaced  by  a  grade  of  char- 
coal specially  prepared  so  as  to  change  the  relative  proportions 
of  the  carbon,  hydrogen,  and  oxygen,  and  also  so  that  the 
burnt  wood  shall  retain  its  fibrous  nature. 

To  this  charcoal  is  also  added  substances  termed  "carbo- 
hydrates," in  which  the  elements  hydrogen  and  oxygen  occur  in 
the  proportions  to  form  water,  which  is  also  one  of  the  objects 
in  preparing  the  charcoal  used,  the  other  object  being  to  have 
the  carbon  in  its  cellular  state,  which  it  retains  even  after  hav- 
ing been  ground  very  fine,  so  as  to  more  readily  combine  with 
the  oxygen  liberated  from  the  nitre  upon  explosion  of  the 
charge.  The  greater  proportion  of  the  oxygen  and  hydrogen 
in  this  charcoal,  and  the  addition  of  the  carbohydrates,  have 
the  following  effect  upon  the  action  of  the  powder: 

The  temperature  after  ignition  of  the  charge  in  the  gun  is 
approximately  4000°  F. — a  degree  of  heat  too  high  to  permit 
hydrogen  and  oxygen  to  unite  to  form  water.  These  ele- 
ments therefore  remain  dissociated  until  the  gases  expand, 
due  to  the  projectile  moving  down  the  bore  of  the  gun.  'This 
expansion  is  accompanied  by  a  fall  of  temperature,  which 
continues  until  a  point  is  reached  at  which  the  hydrogen  and 
oxygen  do  combine  chemically  and  form*water.  This  chemi- 
cal combination  is  in  turn  accompanied  by  evolution  of  heat, 
which  serves  to  convert  the  water  from  a  liquid  into  a  gaseous 
state,  which,  top-ether  with  the  other  gases  formed  during  the 
combustion  of  the  powder,  is  again  expanded,  and  exerts  an 
additional  pressure  upon  the  projectile.  The  pressure  is  thus 
gradually  developed  and  uniformly  sustained  while  the  pro- 
jectile is  in  the  gun,  thereby  insuring  much  higher  velocities 
than  were  possible  under  the  old  conditions. 

Moreover,  the  steam  thus  generated,  which  adds  its  ex- 
pansive force  to  that  of  the  other  gases,  aids  in  dissipating 
the  smoke  consequent  upon  explosion  by  becoming  condensed 
as  soon  as  it  reaches  the  air,  and,  in  the  form  of  water,  ab- 
sorbing a  large  portion  of  potassium  carbonate,  which  forms  a 
large  proportion  of  the  solid  residue  of  the  result  of  decom- 


IOO  LECTURES   ON  EXPLOSIVES. 

position  of  the  powder  and  that  portion  which  appears  as 
smoke. 

The  same  factors  that  tend  to  establish  the  superiority  of 
the  Rottweil-Hamburg  powder  obtain  equally  in  the  brown 
powder  made  in  the  United  States;  while  the  addition  of  the 
carbohydrate  and  the  mode  of  preparing  the  charcoal  also 
serve  to  improve  the  latter  powder.  According  to  Berthelot, 
the  combustion  of  the  hydrocarbons  yields  more  heat  than 
that  corresponding  to  the  carbon  they  contain,  the  hydrogen 
and  oxygen  being  supposed  in  the  state  of  pre-existing  water, 
that  is  to  say,  no  longer  contributing  to  the  production  of 
heat.  The  heat  of  combustion  of  a  carbohydrate  of  the 
formula  C6HpOp  is,  according  to  experiment  (Berthelot),  gen- 
erally from  709  cal.  to  726  cal.  for  72  gm.  of  carbon. 

When  the  carbohydrates  are  dehydrated  by  heat,  a  por- 
tion of  this  excess  of  heat  remains  in  the  residual  carbon, 
which  also  sometimes  retains  an  excess  of  hydrogen  capable 
of  yielding,  weight  for  weight,  four  times  as  much  heat  as 
carbon. 

These  facts,  considered  in  connection  with  the  important 
role  played  by  dissociation,  indicate  other  reasons  for  the 
superiority  of  these  new  powders. 

Amide  Powder* — F.  Gaens  has  proposed  and  patented 
the  use  of  a  gunpowder  differing  from  the  old  gunpowder 
still  more  radically  in  composition  than  brown  powder  does. 
It  consists  of — 

Potassium  nitrate 101  parts. 

Ammonium  nitrate   80     " 

Charcoal 40     ' ' 

The  theory  is  that  when  these  components  are  employed 
in  suitable  proportions,  potassamide,  KH..N,  is  formed  on  igni- 
tion of  the  powder,  that  the  potassamide  is  volatile  at  high 
temperatures,  and  increases  the  useful  effect  of  the  powder. 
The  reaction  is  represented  as  follows : 

KN08+  (NH4)N03+  sC  =  KH,N+  HaO  +  CO  + 


GUNPOWDER.  IOI 

The  patentee  claims  for  this  powder  that  when  burned  it 
leaves  very  little  (if  any)  residue,  produces  no  gases  injurious 
to  the  gun,  and  much  less  smoke  than  ordinary  gunpowder 
does.  This  proposal  is  very  interesting,  and  the  advantages 
claimed  for  the  powder  are  most  important ;  but  there  is  no 
statement  in  chemical  literature  of  the  existence  of  a  potassa- 
mide  volatile  as  such. 

The  explosive  reaction  resulting  from  such  a  mixture 
would  probably  be  represented  as  follows: 

2KN03  +  2(NH4)N03  +  6C  =  K2CO3  +  SCO  +  4H2O  +  3Na, 

the  products  being  those  resulting  from  the  explosion  of  or- 
dinary gunpowder,  the  ammonia  being  oxidized  into  water 
and  nitrogen ;  there  would  also  be  some  interreaction  between 
carbonic  oxide  and  water-vapor  at  high  temperature,  with  the 
formation  of  some  CO2  and  H.  The  volume  of  total  gases 
produced  by  the  ignition  of  such  a  powder  would  be  very 
large,  and  its  rate  of  burning  would  be  likely  to  be  slow 
(from  the  absence  of  S). 

Krupp's  report  of  October,  1888,  contains  an  account 
of  trials  of  new  kinds  of  powder  furnished  by  the  United 
Rhenish-Westphalian  powder  factories.  These  were  of  two 
kinds,  a  large-grain  and  a  prismatic  powder;  their  compo- 
sition is  not  given,  but  from  the  properties  attributed  to  them 
of  giving  but  little  residue,  thin  smoke,  and  of  being  highly 
hygroscopic,  it  is  very  probable  that  they  contain  (NH4)NO3, 
and  are  similar  to  Gaen's  Amide  Powder.  The  grain  pow- 
der, suited  for  use  in  guns  of  small  calibre,  was  tried  in 
guns  of  4-  to  8.7-centimetre  calibre  (i" '.  58  to  $".42),  and 
found  to  give  considerably  less  pressure  in  the  powder-chamber 
for  equal  velocity  than  the  German  service  grain  and  cubical 
powders  which  were  tried  in  comparison,  the  new  powder 
being  stated  to  be  about  ij  to  i-j-  times  as  efficient  as  the  old. 

The  prismatic  powder  suited  for  medium-sized  guns  was 
proved  in  10.5- and  15-centimetre  guns  (4. "13  and  5". 9),  with 
the  result  that  the  new  powder  was  found  to  be  more  efficient 
per  unit  of  weight  than  the  brown  prismatic  powder,  giving 


102  LECTURES   ON  EXPLOSIVES. 

less  pressure  for  the  same  velocity ;  and  it  was  stated  that, 
without  exceeding  a  safe  limit  of  pressure,  the  new  powder 
could  give  velocities  which  could  not  be  reached  by  the  brown 
prismatic  powder. 

Quick  Powder. — Mr.  G.  Quick  has  taken  out  several 
patents  for  improvements  in  cartridges  for  ordnance.  The 
first  (1884)  is  for  the  pressing  of  disks  or  cakes  of  gunpowder 
(or  other  gas-producing  explosive)  with  a  large  central  cylin- 
drical hole  and  smaller  radial  one,  which  are  connected  by 
numerous  radial  and  concentric  channels,  either  formed  on 
the  flat  sides  of  the  cakes  by  suitable  means  in  the  pressing, 
or  subsequently  cut  or  drilled  in  them.  The  object  of  these 
channels  is  stated  to  be  for  the  spread  of  the  flame  equally 
and  rapidly  in  all  directions,  over  and  between  the  surfaces  of 
the  cakes  as  well  as  through  the  perforations  in  them,  so  that 
the  whole  cake  and  the  whole  of  the  charge  may  be  ignited 
with  great  rapidity  and  burnt  with  great  uniformity.  The 
objects,  it  may  be  noted,  differ  from  those  aimed  at  in  the 
Rodman  perforated  cake.  The  central  hole  should  bear  some 
relation  to  the  proposed  diameter  and  the  length  of  the  car- 
tridge ;  the  disks  may  be  of  any  required  thickness,  from  one- 
half  inch,  to  six  or  more  inches,  and  any  number  may  be 
employed  to  form  a  cartridge  or  charge,  the  central  holes 
being  kept  in  the  centre  of  the  cartridge,  and  the  other  holes 
corresponding  to  each  other. 

The  disks  may  be  of  the  same  diameter  as  the  powder- 
chamber  of  the  gun,  or  they  may  be  smaller,  and  the  annular 
space  may  be  filled  with  any  other  description  of  powder. 

One  of  the  specifications  claims  the  use  of  the  solution  of 
guncotton,  or  of  celluloid  or  similar  material,  as  a  cement  or 
water-proof  coating  for  the  individual  cakes  forming  a  car- 
tridge;  and  in  the  1888  specification,  instead  of  disks,  he 
proposes  the  compressing  of  gunpowder  or  other  explosives 
in  the  form  of  segments  of  a  circle  (they  appear  from  the 
drawing  to  be  sectors  of  a  circle),  so  that  when  placed  together 
they  form  rings  or  disks  of  a  diameter  suitable  to  the  powder- 
chamber  of  the  gun.  The  segments  are  provided  with  pro- 


GUNPOWDER.  103 

jections  and  recesses  to  look  the  segments  of  the  cakes  and 
the  individual  cakes  one  to  another,  so  as  to  prevent  any 
twisting  or  sliding  movement;  the  junctions  of  the  segments 
being  so  disposed  that  the  segments  "  break  joint"  with 
respect  one  to  another,  the  whole  thus  forming  a  rigid  cylin- 
drical cartridge  or  charge. 

Noble's  Powder. — In  1886,  Colonel  W.  H.  Noble  pro- 
posed to  build  up  cylindrical  charges  for  guns,  practically  in 
the  same  manner  patented  by  Mr.  Quick  two  years  later. 
Colonel  Noble  also  claims  improvements  in  the  preparation 
of  charcoal  for  gunpowder,  with  a  view  of  obtaining  charcoal 
of  uniform  chemical  composition.  In  charring  wood,  he  pro- 
poses to  previously  crush  it,  to  char  some  of  it  rapidly  and 
some  slowly,  so  as  to  produce  charcoals  containing  different 
percentages  of  carbon,  to  be  ascertained  by  analysis,  and  to 
make  a  blend  of  the  charcoals  in  such  proportion  as  to  furnish 
a  charcoal  containing  the  desired  amount  of  carbon.  He  also 
proposes  to  employ  uncharred  turf  or  bogstuff  (previously 
washed,  dried,  and  ground)  either  alone  or  mixed  with  char- 
coal. 

The  subject  of  smokeless  powders  (except  those  having 
ammonium  nitrate  for  the  base),  at  least  such  as  have  as  yet 
appeared,  belongs  properly  to  the  class  of  explosive  com- 
pounds, and  will  be  considered  subsequently. 

Saxifragine. — -In  this  powder,  barium  nitrate,  Ba(NO3)3,  is 
substituted  for  nitre  with  the  view  of  producing  a  slower- 
burning  gunpowder,  the  proportions  of  the  several  ingredi- 
ents being  as  follows : 

Barium  nitrate 77.00  parts 

Charcoal 21.00      " 

Sulphur 2.00      " 

The  barium  nitrate  used  is  prepared  by  treating  the  chlorate 
with  sodium  nitrate,  and  the  process  of  manufacture  is 
identical  with  that  of  gunpowder.  The  inflammability  of 
the  powder  is  increased  by  dusting  the  grains  of  the  finished 
product  with  meal-powder.  Experiments  with  this  powder 


104  LECTURES   ON  EXPLOSIVES. 

have  proved  it  to  be  unfit  for  a  propelling  agent,  its  rate  of 
combustion  being  too  slow  for  use  in  small-arms,  and  the 
property  of  greatly  fouling  the  bore  precluding  its  use  in 
guns  of  heavy  calibre. 

The  only  advantage  claimed  for  this  class  of  powders  was 
its  low  rate  of  combustion,  an  end  that  can  now  be  accom- 
plished at  will  by  varying  the  physical  characteristics  of 
ordinary  gunpowder,  and  it  has  therefore  almost  entirely  dis- 
appeared. 

Blasting-powders. — Although,  on  account  of  its  hygro- 
scopicity,  sodium  nitrate  cannot  be  used  in  the  manufacture 
of  military  gunpowders  which  are  generally  made  in  large 
quantities  to  be  stored  for  years,  this  substance  appears  as 
the  principal  ingredient  in  a  great  many  powders  which  are 
made  for  immediate  use  in  blasting,  especially  when  such 
powders  are  to  be  used  in  hot  climates.  The  number  of  such 
blasting  agents  is  almost  infinite,  and  only  a  few  need  be 
mentioned  in  order  to  indicate  their  general  character. 

Triumph  Safety  Powder  (Courteilles). — The  composition 
of  this  powder  is  as  follows : 

Sodium  nitrate 67.41  parts 

Sulphur 11.23      " 

Charcoal 7.75      " 

Peat  and  coal 10.  n      " 

Metallic  sulphates  (combined) 2.24      " 

Oleaginous  matter  (animal  or  vegetable)      1.26      " 

The  several  ingredients  are  pulverized  and  thoroughly 
incorporated  in  a  dry  state.  The  mixture  is  next  saturated 
with  steam,  and  finally  subjected  to  the  action  of  superheated 
steam  until  nearly  dry,  the  temperature  being  gradually 
reduced  from  25O°F.  to  I5O°F.  The  remaining  traces  of 
moisture  are  expelled  by  drying  the  powder  on  hot  plates. 
The  advantages  claimed  for  this  powder  are  freedom  from 
explosion  by  friction  or  percussion,  slow  combustion  due  to 
the  use  of  peat,  charcoal,  and  hard  coal,  and  finally  it  is 
claimed  that  the  relatively  great  volume  of  gas  evolved  by  the 


GUNPOWDER.  105 

gunpowder  elements  combines  with  the  correspondingly  small 
volume  of  the  other  ingredients,  and  under  certain  conditions, 
when  the  explosion  occurs  in  a  closed  chamber  or  under 
pressure,  tends  to  form  nitroglycerine  or  other  equivalent  high 
explosives ! 

The  absurdity  of  such  a  claim  is  manifest,  and  this  mix- 
ture is  mentioned  merely  as  an  example  of  many  thousands 
of  such  explosives  whose  wonderful  effects  are  developed  only 
in  the  imagination  of  their  inventors. 

Carbo-azotine,  or  Safety  Blasting-powder. — Several  grades 
of  this  powder  have  been  patented  according  to  the  nature  of 
the  work  to  be  accomplished. 

Soft  Rock  Soft  Coal 

Hard  Rock.  and  and 

Hard  Coal.          Gypsum. 

Potassium  nitrate 70.00  64.00  56.00  parts 

Sulphur 12.00  13.00  14.00     " 

ipblack 5.00  4.00              3.00     " 

>awdust 13.00  19.00  27.00      " 

Ferrous  sulphate 2.00  2.00              5.00     " 

The  ingredients  are  ground  or  pulverized  and  boiled  to- 
gether in  a  weak  solution  of  ferrous  sulphate,  the  result  being 
a  liquid  which  gradually  solidifies. 

When  nearly  solid,  the  mass  is  thoroughly  dried  and 
granulated.  The  powder  may  be  used  in  bulk,  but  is  gener- 
ally issued  in  the  form  of  compressed  cartridges,  and  requires 
strong  confinement  in  order  to  develop  its  full  force. 

Pyrolithe. — The  object  of  this  mixture  was  to  produce  an 
explosive  that  would  develop  no  carbonic  oxide  during  com- 
bustion. Two  grades  have  been  patented,  as  follows: 

Potassium  nitrate Sl-S°   18.00  parts 

Sodium  nitrate 16.00 47.00      " 

Sulphur 20.00   17.00      " 

Sawdust n.oo 12.00     " 

Charcoal 1.50 " 

^Sodium  carbonate  or  sulphate....  6.00     " 


LECTURE   VI. 

GUNPOWDER — Continued. 

Properties  of  Gunpowder. — Good  gunpowder  should  be 
composed  of  hard  angular  grains  which  do  not  soil  the  fingers, 
and  should  hav,e  a  perfectly  uniform  dark  gray  color.  If  the 
color  is  bluish  or  jet-black,  the  powder  contains  an  excess 
either  of  charcoal  or  water. 

The  appearance  of  whitish  or  bluish-white  specks  or  spots 
indicates  that  the  nitre  has  effloresced  during  drying,  or  that 
the  powder  has  absorbed  sufficient  water  to  partially  dissolve 
the  nitre  which  has  accumulated  on  the  surface,  and  in  either 
case  the  incorporation  is  no  longer  uniform. 

When  new  it  should  be  free  from  dust,  and  a  gramme 
of  it  flashed  on  a  copper  or  porcelain  plateshould  leave  no 
residue  or  foulness.  It  should  give  the  required  initial 
velocity  to  the  projectile,  and  produce  not  more  than  the 
maximum  strain  upon  the  gun.  When  exposed  to  air  of 
average  dryness  it  should  not  absorb  more  than  from  0.5  to 
1.5  per  cent  of  water.  In  damp  air  gunpowder  absorbs  a 
much  larger  proportion  of  water,  and  deteriorates  in  conse- 
quence of  the  saltpetre  being  dissolved  and  crystallizing  on 
the  surface  of  the  grains,  while  actual  contact  with  water  dis- 
solves the  saltpetre  entirely  and  disintegrates  the  grains. 

Prismatic  powder  should  present  a  smooth  surface,  sharp, 
well-defined  angles,  and  the  prisms  should  not  crumble  along 
the  edges  when  moderately  rubbed.  The  size  of  the  prisms 
and  the  diameter  of  the  perforations  may  be  measured  by 
standard  gauges  for  that  purpose. 

106 


G  UNPO  WD  ER.  I O/ 

The  property  which  exercises  the  greatest  influence  upon 
the  general  character  of  gunpowder,  and  the  phenomena- 
which  attend  its  application  as  a  propelling  agent,  is  its  density 
— absolute  density  or  specific  gravity.  By  density  is  meant  the 
ratio  which  the  weight  of  a  given  volume  of  the  powder  bears 
to  the  weight  of  an  equal  volume  of  water  at  15°. 5  C.  It 
varies  from  about  1.50  to  1.85.  On  account  of  its  import- 
ance, it  would  be  well  to  consider  this  quality  of  gunpowder 
more  closely.  Density  must  not  be  confounded  with  hard- 
ness. A  substance  may  be  very  hard  and  yet  be  of  a  low 
density.  A  powder  with  a  very  hard  surface  may  be  in 
reality  less  dense  than  another  the  surface  of  which  is  softer. 
Of  course  a  very  high  density  cannot  be  communicated  with- 
out producing  a  considerable  degree  of  hardness;  but  a 
powder  may  be  made  hard  without  rendering  it  very  dense. 
Hardness  seems  to  bear  a  direct  relation  to  the  power  exerted 
in  compressing,  while  density  does  not.  Powder-dust  con- 
taining about  six  per  cent  of  moisture  can  be  made  very  dense 
by  the  application  of  moderate  pressure,  while  that  containing 
one  per  cent  can  be  brought  to  the  same  degree  of  density 
only  by  the  exertion  of  enormous  force;  of  these  powders, 
the  latter  will  be  the  harder. 

Assuming  the  usual  values  assigned  to  the  elements  of 
gunpowder  in  the  scale  of  specific  gravities,  the  absolute 
density  of  a  homogeneous  mass  of  the  mixture  is  1.985.  It 
is  needless  to  say  that  this  point  is  never  reached  in  practical 
manufacture. 

By  subjecting  powder-meal  to  powerful  pressure  its  den- 
sity is  greatly  increased,  and  consequently  a  given  bulk  of 
the  pressed  powder  will  yield  on  combustion  a  much  greater 
volume  of  gas  than  an  equal  bulk  of  mill-cake.  It  becomes 
obvious,  then,  that  the  density  of  the  powder  which  can  be 
varied  at  will  becomes  its  most  important  physical  quality, 
on  account  of  the  great  influence  which  it  exerts  on  its  action 
when  ignited.  It  is  evident  that,  if  different  amounts  of 
material  be  compressed  into  equal  bulks,  the  effect  of  equal 
amounts  of  the  resulting  powder,  whether  by  weight  or 


IO8  LECTURES   ON  EXPLOSIVES. 

volume,  will  not  be  equal.  No  experimental  proof  is  neces- 
sary to  show  that  if  two  grammes  of  powder  of  equal  size,  one 
of  which  is  twice  as  dense  as  the  other,  be  ignited  in  the  open 
air, -the  denser  will  take  a  longer  time  to  burn;  for  the  former 
not  only  has  a  closer  and  less  porous  texture  of  grain,  but 
contains  a  larger  quantity  of  matter,  bulk  for  bulk,  to  be 
burned  from  nearly  the  same  surface,  for  in  this  case  combus- 
tion occurs  under  the  normal  atmospheric  pressure. 

Under  similar  circumstances  and  conditions,  differences  in 
density  may  be  assumed  to  effect  the  following  changes  in  the 
manner  in  which  a  gramme  of  powder  of  average  mammoth 
size  is  consumed  in  a  gun: 

First.  On  ignition  it  takes  fire  all  over  the  surface,  when, 
if  sufficiently  dense,  it  continues  burning  toward  the  centre 
in  concentric  layers  until  it  is  entirely  consumed. 

Second.  If  of  too  low  density  to  resist  the  pressure  to 
which  it  is  exposed  in  the  gun,  the  heated  gases  at  once  pen- 
etrate the  pores,  lighting  their  walls  as  they  advance,  thus 
causing  a  development  of  gas  from  a  surface  many  times 
greater  than  that  which  may  be  called  the  original  external 
surface. 

It  is  therefore  evident  that  uniformity  of  results  and  effect 
cannot  be  obtained  in  fired  gunpowder,  unless  the  density  be 
uniform  and  constant  from  one  discharge  to  another. 

One  of  the  most  serious  difficulties  encountered  in  the  use 
of  gunpowder  arises  from  the  property  of  erosion.  Although 
the  erosive  action  of  gunpowder  occurs  in  the  bore  of  small- 
arms,  it  is  comparatively  limited  in  extent  and,  with  the  older 
forms  of  powder,  becomes  perceptible  only  after  continuous 
firing.  With  the  more  recent  powders,  however,  and  especially 
in  guns  of  heavy  calibre,  this  action  of  the  powder-gases 
upon  the  bore  often  results  from  the  firing  of  a  single  service 
round.  For  some  years  it  was  believed  that  the  cause  of 
trouble  was  to  be  found  in  the  sulphur  contained  in  the 
powder,  and  this  belief  was  supported  by  the  fact  that 
among  the  products  of  combustion  of  gunpowder  are  to  be 
found  free  sulphur  and  a  mixture  of  potassium  polysulphides 


G  UNPO  WDER.  1 09 

and  potassium  carbonate,  which,  at  a  bright  red  or  white  heat, 
exercise  a  powerful  corroding  action  upon  steel  or  iron. 
This  action  would  naturally  vary  with  the  condition  of  the 
surface  of  the  bore,  temperature,  pressure,  and  time  of 
cooling. 

Although  sulphur  may  and  probably  does  contribute  to  the 
erosive  action  of  the  powder-gases,  the  investigations  of 
Nobel  and  Abel  indicate  that  this  is  not  the  sole  cause  of 
trouble,  but  that  an  important  factor  is  to  be  found  in  the 
passage  along  the  surface  of  the  bore  of  the  highly  heated 
and  rapidly  moving  gases  developed  by  explosion  of  the 
charge.  Therefore,  in  order  to  eliminate  this  cause  of  trouble 
as  far  as  possible,  the  nature  and  proportion  of  the  ingredi- 
ents of  the  powder  should  be  such  as  to  produce  the  greatest 
volume  of  gas  with  the  least  amount  of  heat,  and  the  lowest 
pressure  for  the  same  temperature. 

Tests  for  Gunpowder. — From  what  has  been  said,  it  is 
evident  that  certain  defined  physical  and  mechanical  proper- 
ties are  essential  in  order  that  a  uniform  standard  of  results 
may  be  maintained,  and  that  it  is  necessary  that  these  points 
be  determined  with  extreme  accuracy  and  precision  in  the 
case  of  all  military  powders.  The  most  important  determi- 
nations to  be  made  are: 

1.  The  purity  and  proportions  of  the  ingredients,, 

2.  The  hygroscopic  quality  of  the  mixture. 

3.  The  thoroughness  of  incorporation. 

4.  The  granulation  and  hardness. 

5.  The  absolute  density  or  specific  gravity. 

Analysis  of  Gunpowder. — A  complete  analysis  of  gun- 
powder includes  the  estimation  of  the  ingredients,  the  deter- 
mination of  the  nature  of  the  characoal,  and  the  degree  of 
purity  of  the  ingredients.  When  powder  has  been  damaged 
by  moisture  or  otherwise,  or  when  a  powder  of  new  or 
unknown  manufacture  is  to  be  examined,  it  should  be  tested 
qualitatively  for  various  impurities  suggested  by  the  particular 


HO  LECTURES   ON  EXPLOSIVES. 

cases  under  consideration,  and  the  method  of  qualitative 
analysis  to  be  adopted  is  determined  by  the  results.  A 
powder  of  known  manufacture  is  examined  qualitatively  to 
determine  the  essential  constituents  and  the  chlorides  and 
moisture.  The  following  is  the  most  reliable  process.  The 
determination  of  the  nitre  depends  upon  its  solubility  in 
water,  while  charcoal  and  sulphur  are  insoluble.  That  of 
sulphur  depends  upon  its  easy  oxidation  by  means  of  fuming 
nitric  acid  and  potassium  chlorate,  forming  sulphates,  which 
are  estimated  by  precipitation  as  barium  sulphate. 

Three  samples  of  gunpowder  are  weighed  in  rapid  succes- 
sion (in  order  that  the  percentage  of  moisture  determined  for 
one  shall  be  true  for  all)  in  the  following  manner: 

Two  watch-glasses  of  equal  size,  with  a  clamp  to  fasten 
them  together,  are  dried  and  weighed.  A  sample  of  powder 
(5  grammes)  is  then  introduced  and  the  whole  reweighed :  the 
difference  is  the  weight  of  powder  used.  This  sample  (N)  is 
placed  in  a  beaker,  of  about  150  c.c.  capacity,  for  the 
determination  of  the  nitre.  Another  sample  of  powder  of 
the  same  weight  is  introduced  into  the  watch-glasses  and 
weighed  as  before.  This  sample  (S)  is  placed  in  a  tall  narrow 
beaker,  of  about  300  c.c.  capacity,  for  the  determination  of 
the  sulphur.  A  third  sample  of  the  same  weight  is  intro- 
duced into  the  watch-glasses  and  weighed  as  before. 

This  sample  (M)  is  placed,  together  with  the  watch- 
glasses  and  clamp,  in  a  drying-oven,  and  dried,  at  not  exceed- 
ing 60°  C.,  for  about  24  hours.  It  is  then  removed  from  the 
oven,  the  glasses  are  clamped,  and  the  whole  placed  in  the 
scale-case  to  cool.  It  is  then  reweighed.  The  loss  of  weight 
determines  the  moisture. 

Sample  N  is  covered  with  water  (about  50  c.c.)  heated  to 
100°  C.,  and  allowed  to  settle.  Meanwhile  two  filters  of  the 
same  size  are  prepared,  and  their  difference  in  weight  is 
determined.  These  are  to  form  a  double  filter,  the  lighter 
being  always  placed  underneath  for  convenience.  A  wide 
beaker,  of  about  300  c.c.  capacity,  is  also  weighed.  The 


G  UNPO  WD  ER.  Ill 

clear  portion  of  the  solution  is  decanted  on  the  double  filter, 
and  the  filtrate  received  in  the  weighed  beaker.  The  residue 
is  again  treated  with  boiling  water  and  the  operation  repeated. 
The  residue  is  then  washed  from  the  beaker  upon  the  filter 
by  means  of  boiling  water,  being  careful  that  every  particle 
of  residue  is  rinsed  out  of  the  beaker.  The  filtrate  is  evap- 
orated to  dryness  in  a  water-bath,  heated  to  148°  C.  in  an  air- 
bath,  and  weighed.  The  increase  of  weight  determines  the 
nitre  directly. 

The  residue  is  dried  on  the  filter  at  60°  C.  and  weighed 
on  the  upper  filter,  balancing  this  filter  by  means  of  the 
lower.  The  loss  of  weight,  minus  the  difference  in  weight  of 
the  two  filters,  and  corrected  for  moisture,  determines  the 
nitre  by  difference. 

Sample  S  is  covered  with  about  50  c.c.  of  fuming  nitric 
acid,  chemically  pure,  and  brought  to  and  maintained  at  a 
gentle  ebullition.  Small  quantities  of  very  finely  pulverized 
potassium  chlorate  are  added  with  caution,  so  that  the  liquid 
will  not  foam  over,  until  a  clear  solution  is  obtained,  being 
careful  to  add  no  more  chlorate  than  is  necessary  for,  this 
purpose.  If  at  any  time  there  is  a  tendency  to  foam  over, 
the  beaker  should  be  at  once  removed  from  the  heat,  and 
allowed  to  cool.  The  solution  is  allowed  to  cool  and  hydro- 
chloric acid  is  added  in  small  quantities  at  first  from  a  pipette, 
then  as  the  action  decreases  it  is  poured  in,  until  the  amount 
of  liquid  in  the  beaker  is  about  doubled.  The  whole  is 
evaporated  to  dryness,  redissolved  in  about  50  c.c.  of  water, 
made  up  to  exactly  100  c.c.,  which  is  usually  a  sufficient  and 
convenient  quantity,  filtered,  and  the  amount  of  sulphur 
ascertained  by  means  of  a  decinormal  solution  of  barium 
chloride.  A  normal  solution  is  prepared  by  dissolving  244 
grammes  of  the  crystallized  salt,  BaCl,.2H2O,  in  one  litre  of 
water;  the  decinormal  solution  is  prepared  by  diluting  a  por- 
tion of  this  to  ten  times  its  volume. 

To  determine  the  sulphur,  5  c.c.  of  the  solution  contain- 
ing the  sulphates  is  put  into  a  test-tube,  and  a  portion  of  the 


112  LECTURES   ON  EXPLOSIVES. 

decinormal  solution  of  barium  chloride  is  added  from  a 
burette  and  the  tube  well  sha'ken ;  when  the  precipitate  has 
settled  a  drop  or  two  more  is  added,  and  if  cloudiness  is 
produced  more  is  added  until  the  addition  of  a  drop  of  barium 
chloride  no  longer  produces  cloudiness.  Having  thus  ap- 
proximately determined  the  amount  of  barium  chloride 
required  to  precipitate  the  sulphates,  a  series  of  solutions  of 
5  c.c.  of  the  solution  of  sulphates  containing  greater  and  less 
amounts  of  barium  chloride  is  prepared.  Thus  if  7.2  c.c. 
was  found  to  be  the  approximate  amount  required,  the  series 
would  contain  6.8,  7.0,  7.2,  7.4,  7.6,  7.8  c.c.  The  precipi- 
tates are  allowed  to  settle,  and  the  tubes  are  tapped  with  the 
ringer  until  the  bubbles  at  the  top  disappear.  A  few  drops 
of  the  solution  of  barium  chloride  are  then  poured  in  separate 
drops  on  a  clean  violet-  or  ruby-colored  glass  plate,  and  a  few 
drops  of  the  solution  of  sulphates  on  another  portion  of  the 
plate.  A  drop  of  one  of  the  clear  solutions  in  the  test-tubes, 
beginning  usually  with  the  lowest,  is  then  put  on  the  plate 
near  one  of  each  of  the  two  solutions  on  the  plate.  One  of 
the  two  drops  thus  placed  is  let  into  the  drop  of  the  solution 
of  sulphates,  the  other  into  the  drop  of  the  solution  of  barium 
chloride,  by  means  of  a  clean  glass  rod.  If  cloudiness 
appears  in  the  sulphate  solution,  take  the  next  higher  (to 
which  more  barium  chloride  has  been  added),  and  so  on;  if 
cloudiness  appears  in  the  solution  of  sulphates,  take  the  next 
lower  (to  which  less  barium  chloride  has  been  added),  and  so 
on,  until  a  point  is  reached  where  no  cloudiness  is  produced 
in  either  solution. 

In  making  an  analysis  of  U.  S.  regulation  powders,  the 
percentage  of  sulphur  in  the  mixture  being  fixed  as  far  as 
possible,  the  following  method  may  be  substituted  for  that 
just  described,  which,  in  practice,  will  be  found  to  require 
very  delicate  manipulation.  The  amount  of  sulphur  in  these 
powders  may  be  assumed  to  be  10  per  cent,  which  for  the 
amount  under  analysis  (5  grammes)  will  be  0.5  gramme  or 
500  milligrammes. 


G  UNPO  WDER.  113 

From  the  reaction  M2SO4  +  BaCl2  =  BaSO4  +  2  MCI  it 
is  evident  that  every  molecule  of  barium  chloride  detects  one 
atom  of  sulphur;  hence  every  cubic  centimetre  of  normal 
solution  of  barium  chloride  (since  it  contains  a  number  of 
milligrammes  of  barium  chloride  equal  to  its  molecular  weight) 
is  equivalent  to  a  number  of  milligrammes  of  sulphur  equal  to 
its  atomic  weight,  or  32.  Every  c.c.  of  a  decinormal  solution 
will  then  be  equivalent  to  f~|  mg.  sulphur.  There  were 
100  c.c.  of  the  solution  of  sulphates,  5  of  which  were  used  in 
the  determination;  hence  ff  X  20  X  the  number  of  c.c.  of 
barium  chloride  solution  used  determines  the  weight  of  the 
sulphur  in  milligrammes. 

To  determine,  then,  the  several  amounts  of  BaCl2  to  be 
added  to  each  test-tube  in  order  to  form  the  first  approximate 
series,  we  may  substitute  in  the  last  expression 

ff  X  20  X  x  =  500,     or     x  =  7.8. 

Hence  we  may  now  make  our  first  approximation  by  adding 
to  the  six  tubes  in  succession  7.4,  7.6,  7.8,  8.O,  8.2,  and  8.4 
c.c.  respectively.  They  are  then  placed  in  a  test-tube  holder 
and  the  precipitates  allowed  to  settle.  A  few  drops  of  the 
Bad,  solution  are  then  introduced  into  each  tube  by  means 
of  a  pipette  until  two  consecutive  tubes  are  found,  in  one  of 
which  an  additional  precipitate  of  BaSO4  is  formed,  while  the 
other  remains  perfectly  clear. 

The  result  of  this  operation,  which  consumes  but  a  few 
minutes,  enables  us  to  form  a  second  series  of  solutions  of  5 
c.c.  each,  in  which  the  approximation  is  so  close  that  the 
result  may  be  accepted  as  practically  exact.  Suppose  that, 
as  a  result  of  the  first  approximation,  the  two  consecutive 
tubes  were  those  in  which  7.8  and  8.0  c.c.  of  the  BaCl2  solu- 
tion had  been  added.  We  then  proceed  to  form  a  second 
series  of  solutions  by  adding  7.7,  7.8,  7.9,  8.0,  8.1,  and  8.2 
c.c.  of  the  BaCla  solution  to  the  several  tubes  in  succession. 
Allow  the  precipitates  to  settle,  and  proceed  as  before.  In 
this  way  the  degree  of  approximation  is  very  close,  while  in 


114  LECTURES   ON  EXPLOSIVES. 

practice  it  has  been  found  much  easier  to  detect  the  exact 
point  at  which  all  of  the  BaSO4  has  been  precipitated  than 
in  the  manner  previously  described. 

The  charcoal  may  be  determined  (a)  as  follows:  The  filter 
containing  the  sulphur  and  charcoal  after  the  nitre  has  been 
extracted  is  thoroughly  moistened  with  warm  water,  and  the 
neck  of  the  funnel  containing  the  filter  closed  temporarily 
with  a  cork. 

The  residue  on  the  filter  is  moistened  with  alcohol,  and 
then  covered  with  carbon  bisulphide  and  allowed  to  digest  for 
two  hours,  covering  the  funnel  with  a  ground-glass  plate. 
At  the  end  of  two  hours  the  liquid  is  drawn  off,  and  the 
process  of  digestion  repeated  until  a  drop  of  the  liquid  evap- 
orated upon  a  piece  of  clean  platinum-foil  leaves  no  residue. 
The  filter  is  dried  and  weighed,  and  the  difference  in  weight 
between  the  filter  alone  and  the  filter  with  residue  will  be  the 
weight  of  charcoal.  By  collecting  the  bisulphide  solution  in 
a  weighed  flask,  evaporating  upon  a  water-bath  at  between 
70°  and  80°  C.,  further  heating  the  contents  of  the  flask  up 
to  the  point  of  fusion,  and  driving  off  the  carbon  bisulphide 
vapors  by  a  current  of  dry  air,  the  weight  of  sulphur  may  be 
very  closely  determined,  the  slight  error  being  due  to  a  small 
percentage  of  allotropic  sulphur  present  in  the  powder  which 
is  insoluble  in  carbon  bisulphide. 

The  charcoal  may  also  be  determined  (b)  by  extracting  the 
nitre  from  one  sample  and  subtracting  from  the  weight  of  the 
residue  that  of  the  sulphur  found  in  an  equal  weight  of 
another  sample. 

The  chlorides  are  determined  by  redissolving  the  nitre 
obtained  in  the  estimation  of  nitre  by  the  direct  method  in 
the  smallest  quantity  of  water,  and  proceeding  as  in  the 
estimation  of  chlorides  explained  under  Nitre. 

The  following  example  will  illustrate  the  method  of  analy- 
sis just  described  and  the  form  of  record: 


GUNPOWDER.  115 

DEPARTMENT    OF    CHEMISTRY    AND    EXPLOSIVES. 

ANALYSIS   OF  GUNPOWDER. 

FORT  MONROE,  VA  ,  April  22,  1889. 

Kind  of  Powder  :    Hexagonal,  E.  V.  D.  (Du  Pont). 

Milligrammes. 

Weight  of  watch-crystals  +  clamp 19804 

Weight  of  watch  crystals,  clamp  -J-  powder 24804 

Weight  of  watch-crystals,  clamp  -j-  powder  dry 24745 

Moisture 59 

Percentage  of  moisture,  5000  :  59  ::  100  :  x  =  1.18  per  cent. 

Weight  of  powder  corrected  for  moisture 4941 

Weight  of  beaker  -f-  nitre 86961 

WTeight  of  beaker 83300 

Weight  of  nitre — direct 3661 

Percentage  of  nitre  (direct},  4941  :  3661  ::  100 :  x  =  74.094  per  cent. 

Difference  in  weight  of  filters  +  residue 1334 

Difference  in  weight  of  filters 50 

Weight  of  residue 1284 

Weight  of  nitre — by  difference  (4941  —  1284) 3657 

Percentage  of  nitre  (by  difference),  4941  :  3657  ::  100  :  x  =         74.013  per  cent. 

Weight  of  powder  corrected  for  moisture 4941 

Sulphate  solution  measures  no  c.c. 

Amount  tested,  5  c.c.,  required  7  7  cc.  -  — BaCl2. 

Weight  of  sulphur,  7.7  X  0.0032  X  22  =  542 

Percentage  of  sulphur,  4941  :  542  ::  100  :  x  =  10.971  per  cent. 

Weight  of  residue 1284 

Weight  of  sulphur 542 

Weight  of  charcoal 742 

Percentage  of  charcoal,  4941  :  742  ::  100  :  x  =  15.015  per  cent. 

Percentage  of  nitre  (direct) 74.094             (by  din0.)  74.013 

Percentage  of  sulphur 10.971  10.971 

Percentage  of  charcoal  (a) 14-945  (6)           15.015 


TOO  ooo  99.999 

Determination  of  the  Hygroscopic  Quality  of  the  Pow- 
der.— The  amount  and  percentage  of  moisture  in  the  powder 
is  determined  as  has  just  been  described  in  the  analysis  of 
gunpowder.  The  ability 'to  resist  moisture  is  determined  by 
subjecting  samples  of  the  powder,  which  have  been  dried,  to 
exposure,  first,  in  the  open  air;  second,  in  the  hygroscope 
containing  a  solution  of  saltpetre  made  at  100°  and  cooled 
down  to  80°  F. 


Il6  LECTURES   ON  EXPLOSIVES. 

The  hygroscope  is  an  air-tight  box  arranged  to  contain 
specimens  of  powder,  while  subjecting  them  to  a  damp 
atmosphere  at  nearly  uniform  temperatures  for  24  hours.  It 
consists  of  two  parts,  an  inner  compartment  of  copper  (about 
12"  X  12")  and  the  outer  case  of  wood,  the  two  being  sepa- 
rated by  a  space  of  two  inches  which  is  solidly  packed  with 
hair.  The  top  or  lid  is  also  double  and  made  non-conduct- 
ing by  hair  packing,  the  lower  face  being  of  copper  and  fitting 
closely  to  the  sides  of  the  inner  compartment.  As  an  addi- 
tional precaution,  an  india-rubber  gasket  extends  around  the 
top  of  the  outer  case,  and  the  top  is  drawn  into  very  close 
contact  with  this  by  means  of  thumbscrews.  A  movable 
tray  of  copper,  the  bottom  of  which  is  perforated,  rests  upon 
projections  from  the  walls  of  the  inner  compartment. 

The  powder  to  be  tested  is  placed  in  circular  cups,  one 
inch  in  depth  and  three  inches  in  diameter,  which  are  fitted 
with  wire-gauze  bottoms  of  sufficiently  small  mesh  to  contain 
the  finest-grained  powder.  The  percentage  of  gain  is  deter- 
mined by  weighing  in  carefully  prepared  bottles,  into  which 
the  powder  is  introduced  as  soon  as  the  hygroscope  is  opened. 

The  influence  of  atmospheric  conditions  on  the  quantity 
of  moisture  absorbed  by  the  powder  is  so  great  that  accuracy 
requires  that  a  careful  record  be  kept  of  the  barometer, 
hygrometer,  external  thermometer,  and  of  a  maximum  and 
minimum  thermometer,  fitted  inside  of  the  hygroscope  when- 
ever samples  are  being  tested,  and  in  each  case  reference 
should  be  made  to  tables  previously  worked  out  in  the  case 
of  a  standard  powder  of  like  specific  gravity,  and  granulation 
under  like  conditions. 

Test  for  Proper  Incorporation. — Thoroughly  incorpo- 
rated powder  presents  a  perfectly  homogeneous  appearance, 
and  upon  breaking  up  a  granule  it  should  show  an  ashen-gray 
color,  and  the  texture  should  be  very  close;  a  granular 
appearance,  and  especially  the  presence  of  any  white  specks, 
is  inadmissible.  This  examination  should  be  made  with  the 
assistance  of  a  magnifying  glass. 

The  flashing  of  a  gramme  or  so  of  the  powder  on  a  copper 


GUNPOWDER.  117 

or  porcelain  plate  has  been  alluded  to;  but  to  form  an  accu- 
rate judgment,  and  especially  to  compare  the  degrees  of  in- 
corporation of  different  powders,  by  this  test,  requires  great 
care  and  experience.  As  an  improvement  upon  this  rather 
crude  test,  Colonel  Chabrier  proposed  what  he  termed  a 
"  Pyrographic  Method  for  the  Examination  of  Gunpowder." 
This  method  consists  in  flashing  the  powder  on  sheets  of  paper 
colored  blue  with  iodide  of  starch,  the  result  being  a  bleach- 
ing of  the  paper  in  spots  and  streaks.  From  the  size,  shape, 
and  general  appearance  and  arrangement  of  the  spots  and 
streaks,  the  character  of  the  powder  is  determined. 

This  process  is  an  advance  upon  the  original  one,  but 
practically  considerable  difficulty  was  encountered  in  the 
preparation  of  the  paper  before  use,  and  the  preservation  of 
the  record  thereon  after  the  test  had  been  applied. 

The  following  method  of  applying  the  "  Flashing  Test  " 
has  been  proposed  by  Professor  Munroe  of  the  U.  S.  Naval 
Torpedo  Station,  and  has  given  excellent  results. 

Instead  of  the  iodide-of-starch  paper,  he  employs  a  paper 
colored  with  Turnbull's  blue,  which  is  decomposed  (and  its 
color  thereby  destroyed)  by  solutions  of  the  alkalies  and  the 
alkaline  carbonates.  The  alkaline  sulphides  and  thiosulphates 
also  act  upon  this  paper  with  the  partial  production  of  a 
yellow  color;  therefore  by  flashing  gunpowder  upon  such 
paper  yellow  and  white  spots  will  be  formed.  The  test  is 
made  as  follows: 

Pieces  of  the  paper,  6  or  8  inches  square,  are  dampened 
and  placed  on  a  glass  or  porcelain  plate.  A  small  truncated 
leaden  cone  (3  grammes  in  capacity)  is  closed  at  the  smaller 
end  with  the  finger  and  filled  evenly  with  the  powder  to  be 
tested.  The  powder  is  placed  upon  the  paper  by  inverting 
the  cone  carefully  so  as  to  produce  a  conical  heap,  which  is 
immediately  fired  either  by  a  heated  iron  or  copper  wire,  or, 
better  still,  by  a  fine  platinum  wire  heated  to  incandescence 
by  an  electric  current.  The  paper  is  exposed  to  the  action  of 
the  residue  for  30  seconds,  and  then  washed  in  running  water. 

When   pulverized   mill-cake   is   flashed   in   this  way,    the 


n8 


LECTURES   ON  EXPLOSIVES. 


space  described  by  the  base  of  the  cone  will  be  blackened  and 
partially  bleached  by  the  dampened  layers  of  powder  in  con- 
tact with  it;  next  above  this  space  will  be  black  smutches  and 
streaks,  while  the  whole  surface  of  the  paper  will  be  covered 
with  white  and  yellow  spots.  With  badly  incorporated  pow- 
ders these  spots  are  coarse  and  irregular  in  shape  and  dis- 
tribution, while  in  the  case  of  thoroughly  incorporated 
powders  the  spots  are  fine  and  so  evenly  distributed  over  the 
surface  of  the  paper  that  it  appears  merely  of  a  paler  color 
with  occasional  spots  and  streaks. 

Granulation  and  Hardness. — The  size  of  the  grain  is 
determined  by  standard  sieves  made  of  sheet  brass.  Two 
sieves  are  used  for  each  kind  of  powder,  and  the  diameters  of 
the  holes  are  as  follows: 


Kind  of  Powder. 

No. 

Diameter. 

No. 

Diameter. 

Musket    

j 

o"  o^ 

2 

o"  10 

c 

o".2^ 

6 

O"  7H 

g 

The  dimensions  of  the  special  powders  have  been  given 
elsewhere.  The  shape  of  the  grains  can  be  judged  only  by 
the  eye,  but  the  more  recent  powders  belong  to  the  class 
known  as  Powders  of  Regular  Granulation  and  are  very  uni- 
form in  shape;  however,  a  compact  shape  approaching  a  cube 
or  sphere  is  preferable,  and  elongated  flat  scales  are  very 
undesirable.  The  hardness  can  be  determined  only  approxi- 
mately, since  the  hardest-grained  powder  is  considerably 
below  any  scale  used  for  determining  this  quality.  Experi- 
ence in  this  matter  is  the  only  guide,  and  it  is  a  very  diffi- 
cult thing  to  determine  the  relative  hardness  of  the  various 
powders. ' 

On  account  of  the  importance  of  the  exact  determination 
of  the  density  of  powder,  I  have  decided  to  devote  an  entire 
lecture  to  that  subject,  and  will  merely  add  a  few  words  of 
precaution  as  to  the  care  of  gunpowder. 


GUNPOWDER.  119 

Preservation,  Storage,  and  Transportation  of  Gun- 
powder.— Before  leaving  the  subject  of  gunpowder,  it  remains 
to  add  a  few  precautions  as  to  its  preservation,  storage,  and 
transportation.  Government  powder  is  packed  in  barrels  of 
100  pounds  each.  Powder-barrels  are  made  of  well-seasoned 
white  oak  and  hooped  with  hickory  or  cedar  hoops,  which 
should  be  deprived  of  their  bark.  The  hoops  should  cover 
two  thirds  of  the  barrel.  Instead  of  a  bung  on  one  side,  a 
screw-hole  ij-  inches  in  diameter  is  made  in  the  head  of  the 
barrel  for  mortar-  and  musket-powder;  it  is  closed  by  a  wood- 
screw  with  an  octagonal  head  which  must  not  project  beyond 
the  ends  of  the  staves;  under  the  head  of  the  screw  is  a 
leather  washer  steeped  in  a  solution  of  beeswax  in  turpentine. 
The  interior  of  the  barrels  may  be  lined  with  paper,  painted 
or  shellacked  to  render  them  more  impervious  to  moisture.* 

For  transportation,  a  piece  of  cloth  should  be  glued  over 
the  head  of  the  screw.  Powder-barrels  may  be  hooped  with 
copper;  and  boxes  lined  with  galvanized  iron  and  copper  with 
large  screw-lids  have  also  been  tried  as  substitutes  for  the 
ordinary  barrel.  The  heads  of  each  barrel  are  painted  black, 
and  on  them  are  marked  (in  white  oil-paint)  the  number  of 
the  barrel,  the  name  of  the  manufacturer,  the  year  of  fabrica- 
tion, the  kind  of  powder,  the  mean  initial  velocity,  the 
pressure  per  square  inch,  and  the  density.  The  barrels 
should  be  placed  so  that  marks  on  each  can  be  easily  seen. 

In  Germany  the  kind  of  powder  contained  in  a  barrel  is 
plainly  shown  by  means  of  different-colored  labels;  those 
containing  rifle-powder  have  yellow,  cannon-powder  red,  and 
meal-powder  white  labels. 

In  powder-magazines  the  barrels  are  generally  placed  on 
their  sides,  three  tiers  high,  or  even  four  tiers  if  necessary. 
Small  skids  should  be  placed  on  the  floor  and  between  the 

*  In  iy8oa  curious  and  interesting  experiment  was  tried  in  Hanover  with 
the  view  of  protecting  the  contents  of  powder-barrels  from  moisture. 
Barrels  containing  powder  were  covered  by  pasting  on  the  outside  well- 
glued  paper  that  had  been  soaked  in  alum  and  then  dipped  into  pitch. 
The  barrels  were  then  immersed  in  water  for  a  month,  and  upon  examina- 
tion the  powder  was  found  to  be  unimpaired. 


120  LECTURES   ON  EXPLOSIVES. 

several  tiers  of  barrels  in  order  to  steady  them,  and  chocks 
should  be  placed  at  intervals  on  the  skids  to  prevent  the  roll- 
ing of  the  barrels.  The  barrels  should  be  turned  at  least  once 
in  three  months  to  prevent  the  powder  from  caking.  This 
is  done  by  taking  down  one  or  two  barrels  from  each  row,  and 
rolling  the  rest  back  and  forth,  and  then  replacing  the  barrels 
which  had  been  removed. 

The  powder  should  be  separated  according  to  its  kind,  the 
place  and  date  of  fabrication,  and  the  proof  range.  Fixed 
ammunition,  especially  for  cannon,  should  not  be  put  in  the 
same  magazine  with  powder  in  barrels,  if  it  can  be  avoided. 

Igniters,  fuzes,  detonators,  primers,  percussion-caps,  fire- 
works, etc.,  should  never  be  stored  in  powder-magazines. 

In  a  room  13  or  14  feet  wide  the  barrels  may  be  arranged 
in  a  double  row  in  the  centre,  two^  alleys  2\  feet  wide,  and 
two  single  rows  6  to  12  inches  from  the  walls;  in  this  way 
the  marks  of  each  barrel  may  be  seen,  and  any  barrel  can  be 
easily  reached.  In  a  room  12  feet  wide  an  equal  number  of 
barrels  may  be  placed  in  two  double  rows,  with  a  central  alley 
of  3  feet,  and  two  side  alleys,  next  the  walls,  of  about  10  inches 
each.  There  should  be  an  unencumbered  space  of  6  or  8  feet 
at  the  door  or  doors  of  the  magazine. 

Should  it  be  necessary  to  pile  the  barrels  more  than  four 
tiers  high,  the  upper  tiers  should  be  supported  by  a  frame 
resting  on  the  floor;  or  the  barrels  may  be  placed  on  their 
heads,  with  boards  between  the  tiers. 

Besides  being  recorded  in  the  magazine  book,  each  parcel 
of  powder  should  be  inscribed  on  a  ticket  attached  to  the 
pile,  showing  the  entries  and  the  issues. 

For  the  preservation  of  the  powder  and  of  the  floors  and 
lining  of  the  magazine,  it  is  of  the  greatest  importance  to 
preserve  unobstructed  the  circulation  of  air  under  the  flooring 
as  well  as  above.  The  magazine  should  be  opened  and  aired 
in  clear  dry  weather,  when  tJie  temperature  of  the  air  outside 
is  lower  than  that  inside  the  magazine.  It  should  not  be 
opened  in  damp  weather  if  it  can  be  avoided.  The  ventilators 
must  be  kept  free;  no  shrubbery  or  trees  should  be  allowed 


GUNPOWDER.  121 

to  grow  so  near  as  to  protect  the  building  from  the  sun.  The 
magazine  yard  should  be  paved  and  well  drained.  The 
moisture  of  a  magazine  may  be  absorbed  by  chloride  of  cal- 
cium suspended  in  an  open  box  under  the  arch,  and  renewed 
from  time  to  time;  quicklime  is  dangerous  and  should  not  be 
used. 

The  sentinel  or  guard  at  a  magazine,  when  it  is  open, 
should  have  no  fire-arms,  and  every  one  who  enters  the 
magazine  should  take  off  his  shoes,  enter  barefooted,  or  wear 
slippers  made  of  buckskin;  no  sword  or  cane  or  anything 
which  might  occasion  sparks  should  be  carried  in. 

The  windows  should  have  inside  shutters  of  copper  wire- 
cloth.  Fire  should  never  be  kindled  near  the  magazine  for 
the  repair  of  the  roof  or  lightning-rods. 

Barrels  of  powder  should  not  be  rolled  for  transportation; 
they  should  be  carried  in  hand-barrows,  or  slings  made  of 
rope  or  leather.  In  moving  powder  in  the  magazine  a  cloth 
or  carpet  should  be  spread;  all  instruments  used  there  should 
be  of  wood  or  copper,  and  the  barrels  should  never  be 
repaired  in  the  magazine. 

In  the  spring  an  inspection  of  the  barrels  should  be  made, 
and  the  hoops  swept  with  a  brush  wherever  they  can  be  got 
at,  to  remove  the  insects  which  deposit  their  eggs  at  this 
season. 

In  wagons,  barrels  of  powder  must  be  packed  in  straw, 
secured  in  such  a  manner  as  not  to  rub  against  each  other, 
and  the  load  covered  with  thick  canvas. 

In  transportation  by  railroad,  each  barrel  should  be  care- 
fully boxed  and  packed,  so  as  to  avoid  all  friction.  The 
barrels  should  have  a  thick  paulin  under  them.  The  cars 
should  have  springs  similar  to  those  of  passenger-cars. 


LECTURE  VII. 

DENSIMETRY. 

DENSIMETRY  is  the  term  applied  to  the  operation  of  de- 
termining the  density  of  gunpowder,  the  apparatus  used  being 
known  as  densimeters.  In  this  connection  the  term  density 
has  itself  been  loosely  applied,  and  has  been  variously  under- 
stood to  refer  to  the  relative,  absolute,  or  gravimetric  density 
of  gunpowder.  In  the  earlier  attempts  to  determine  the 
relative  density  of  powders,  liquids  exercising  the  minimum 
solvent  effect  upon  the  powders  were  tried,  but  only  approxi- 
mate results  were  obtained. 

One  of  the  first  efforts  consisted  in  filling  a  carefully  cali- 
brated and  graduated  glass  jar  with  absolute  alcohol  until  the 
liquid  occupied  a  certain  volume,  and  after  allowing  sufficient 
time  for  any  drops  adhering  to  the  sides  of  the  jar  to  run 
down,  and  carefully  noting  the  volume  occupied,  a  weighed 
quantity  of  powder  was  introduced  into  the  jar  by  means  of  a 
wide-stemmed  glass  funnel,  and  the  new  volume  occupied  by 
the  alcohol  and  powder  was  noted.  From  the  data  thus 
obtained  it  was  assumed  that  the  relative  density  or  specific 
gravity  could  be  easily  calculated. 

With  all  possible  care,  however,  this  method  was  but  a 
crude  approximation  on  account  of  the  absorption  of  the 
alcohol  by  the  grains  of  powder  with  the  consequent  expul- 
sion of  air  from  the  pores  of  the  grains  caused  by  this  absorp- 
tion. According  to  the  character  of  the  powder,  whether 
glazed  or  unglazed,  tough  or  porous,  the  action  of  the  alcohol 
was  more  or  less  rapid,  and  therefore,  according  to  the  opera- 
tor and  the  time  consumed  in  the  operation,  the  relative 

122 


DEN  SI  ME  TRY.  1 2  3 

density  varied  so  that  a  powder  of  very  low  density  was  made 
to  appear  to  have  an  extremely  high  one,  or  the  reverse. 

Various  other  methods  were  proposed  and  tried,  and 
numerous  densimeters  were  invented,  notably  Marchand's, 
Hoffmann's,  Bode's,  Ricq's,  and  others,  all  of  which  possessed 
merits,  but  generally  counterbalancing  defects.  The  first 
practical  densimeter  by  means  of  which  reliable  and  uniform 
results  were  obtained  was  invented  by  Bianchi,  and  in  a 
modified  form  is  still  used  under  the  name  of  Mallet's  Mer- 
curial Densimeter. 

The  Mallet  Densimeter. — This  apparatus  is  used  at  the 
Artillery  School  for  the  determination  of  the  density  of  rifle-, 
mortar-,  and  cannon-powders  used  in  field-guns.  It  consists 
of  a  small  table  to  one  end  of  which  is  firmly  secured  an  iron 
standard,  to  which  is  attached  a  barometer-tube  of  peculiar 
make;  instead  of  being  of  a  single  piece  and  closed  at  the 
upper  end,  it  is  made  of  two  separate  pieces  and  open  at  the 
top.  The  upper  part  is  about  24  inches  in  length  and  is  con- 
nected to  the  lower,  which  is  10  inches  in  length,  by- means  of 
a  closely  fitting  and  perfectly  air-tight  screwed  metal  joint; 
the  lower  part,  instead  of  being  a  plain  parallel  tube  of  the 
same  diameter  throughout  as  the  upper,  is  made  in  the  form 
of  a  globe  or  bulb  (vase).  To  each  end  of  this  globe  is 
attached  a  metal  collar  fitted  with  female  screw-threads,  and 
the  connections  between  the  barometer-tube  above  and  the 
nozzle  below  are  by  metal  plugs  accurately  fitted  to  these 
threads.  The  upper  plug  is  fitted  with  a  fine  gauze  dia- 
phragm, which  prevents  grains  or  particles  of  powder  from 
entering  the  upper  part  of  the  tube,  while  the  lower  plug  is 
similarly  fitted  with  a  diaphragm  of  chamois-skin,  which 
strains  and  cleans  the  mercury  before  it  enters  the  globe. 
The  nozzle  mentioned  above  screws  into  the  lower  plug  and 
dips  into  the  mercury.  The  lower  extremity  of  the  upper 
part  of  the  tube  and  both  plugs  are  fitted  with  air-tight  stop- 
cocks. 

The  mercury  is  contained  in  a  heavy  porcelain  dish  which 
can  be  raised  or  lowered  by  means  of  a  hand-screw,  so  as  to 


124  LECTURES   ON  EXPLOSIVES. 

keep  the  tip  of  the  nozzle  immersed  to  the  proper  depth. 
The  upper  part  of  the  tube  is  attached  to  a  scale,  which  in 
turn  is  attached  to  the  standard.  To  the  opposite  end  of  the 
table  is  attached  an  air-pump  of  ordinary  construction.  The 
vacuum-gauge  is  in  an  air-tight  glass  case,  which  is  placed 
between  the  standards  on  which  the  brake  works;  it  can  be 
shut  off  from  connection  with  the -cylinder  by  a  stop-cock, 
and  air  is  admitted  to  it  and  thence  to  the  cylinder,  etc.,  by 
unscrewing  the  glass  cover,  which  can  be  turned  by  means  of 
a  chamfered  ring  on  the  brass  collar  into  which  it  fits. 

Connection  with  the  densimeter  is  controlled  by  a  stop- 
cock under  the  bell-glass  table.  The  cylinder  (of  brass) 
oscillates  on  trunnions  at  its  base;  its  connections  with  the 
vacuum-gauge  and  the  densimeter  are  by  means  of  rubber 
hose.  The  cylinder-head  is  fitted  with  an  oil-hole  closed  by 
a  screw-plug,  and  has  an  overflow-can  to  catch  the  oil  forced 
out  in  exhausting.  To  prevent  any  mercury  which  might  find 
its  way  from  the  top  of  the  barometer-tube  from  flowing  into 
the  air-pump,  the  densimeter  and  air-pump  are  connected  by 
hose  through  the  medium  of  a  "  catch-bottle,"  into  which 
the  escaping  mercury  may  overflow  without  damage. 

The  balance  employed  in  connection  with  the  densimeter 
is  a  beam-scale  constructed  with  great  accuracy.  It  consists 
of  a  beam  of  brass  mounted  on  a  hollow  standard  with  ordi- 
nary scale-pans.  The  beam  and  scale-pans  are  supported  on 
steel  knife-edges.  The  beam,  when  not  in  use,  rests  upon 
the  top  of  the  standard,  the  weight  of  the  scale-pans  being 
taken  from  their  knife-edges  by  the  base  of  support  of  the 
standard.  The  central  knife-edge,  when  the  beam  is  not  in 
action,  rests  in  V's  in  the  head  of  the  standard,  but  bears  no 
weight.  The  beam  is  thrown  in  and  out  of  action  by  means 
of  a  lever  at  the  foot  of  the  standard,  which  acts  on  a  stout 
rod  running  up  through  the  standard.  To  the  upper  ex- 
tremity of  this  rod  is  attached  a  double  cross-head,  the  upper 
surfaces  of  which  are  faced  with  polished  hardened  steel,  and 
on  these  surfaces  the  pivoting  or  central  knife-edge  rests  in 
weighing.  A  pointer  extends  from  the  beam  downwards, 


DENS  I  ME  TR  Y.  125 

and  the  oscillations  are  marked  by  a  scale  attached  to  the  foot 
of  the  standard.  To  the  .  base  of  support  is  attached  a 
German  level,  and  the  base  itself  is  furnished  with  levelling- 
screws,  by  means  of  which  the  apparatus  may  be  levelled. 

Precautions  to  be  Observed  in  Using  the  Densimeter. — 
I.  As  all  of  the  different  connections  of  the  globe,  where 
air-tight  joints  are  made,  are  fitted  with  leather  washers  of 
constantly  changing  thickness,  it  follows  that  a  variable 
degree  of  screwing  up  is  required  in  order  to  make  the  junc- 
tions absolutely  perfect.  With  the  plugs  which  screw  into 
the  ends  of  the  globe,  it  is  of  great  importance  that  the 
extent  to  which  they  enter  should  be  uniform  for  any  given 
number  of  trials  with  the  same  powder;  that  is,  they  should 
be  run  in  to  the  same  distance  when  each  sample  of  powder 
is  tried  that  they  were  when  the  globe  was  filled  with  mer- 
cury alone,  for  if  not  in  far  enough  the  capacity  of  the  globe 
is  increased,  and  if  in  too  far  it  is  reduced. 

In  order  to  eliminate  this  source  of  error  as  far  as  possi- 
ble, set-marks  are  put  on  the  collars  and  plugs.  So  long  as 
these  are  either  brought  together  or  kept  separated  by  a  fixed 
and  constant  amount  during  the  different  trials,  the  experi- 
ment will  be  accurate.  As  coincidence  will  probably  only 
occur  when  the  washers  are  new,  the  separation  as  they  wear 
away  or  become  compressed  must  be  determined  for  the 
several  trials  from  which  the  determination  of  the  density  of 
any  given  sample  of  powder  is  to  be  calculated,  and  retained 
throughout  those  trials. 

2.  In  screwing  on  the  nozzle  and  in  screwing  in  the  plugs, 
both  wrenches  should  be  used — one  as  a  spanner,  to  hold 
against  the  other  used  as  a  wrench,  otherwise  the  cementing 
of  the  collars  may  be  started  and  leaks  produced.  Attached 
to  the  table  of  the  densimeter  used  at  the  Artillery  School  is 
a  seat  so  arranged  with  projecting  studs  that  the  globe  may 
be  placed  therein  and  firmly  held  by  the  collars  while  the 
plugs  and  nozzle  are  being  attached  to  or  detached  from  the 
globe,  so  that  all  wrenching  or  twisting  is  removed  from  the 
cemented  joints  between  the  globe  and  collars. 


126  LECTURES   ON  EXPLOSIVES. 

3.  The  zero  of  the  scale  attached  to  the  upper  part  of  the 
barometer-tube  is  the  lower  end  of  the  nozzle.      The  quantity 
of  mercury  in  the  dish  and  the  level  on  which  the  dish  rests 
should  be  so  regulated  that  the  immersion  of  the  nozzle  will 
not  be  greater  when  the  globe    is  full  than  is  necessary  to 
prevent  the  admission  of  air.      This  is  necessary  in  order  to 
avoid   fluctuations   in  the  height  of  the  barometric  column, 
which  are  misleading  as  to  the  condition  of  the  instrument. 

4.  When  leaks  in  the  connections  of  the  globe  occur  they 
are   indicated   by  air-bubbles,  which   can  be  distinctly  seen 
passing  up  through  the  enclosed  mercury.    They  can  generally 
be  located,  if  about  the  junctions,  by  closing  the  cocks  in  suc- 
cession, beginning  at  the  lowest  and  exhausting  at  the  same 
time  by  means  of  the  air-pump.      If  the  leak  be  about  the 
tube-connections,    the  air  will  continue  to  flow  with  all  the 
cocks  closed;    if   it   be   below   this   point,  it   can   be   located 
between   the   cocks.      By  tightening   the   junctions  with  the 
wrenches,  or,  if  in  the  cocks,   by  screwing  them   up  with  a 
screw-driver,  the  difficulty  is  remedied. 

It  sometimes  happens  that  the  cement  which  holds  the 
collar  to  the  neck  of  the  globe  becomes  cracked  and  produces 
a  leak;  this  can  be  located  by  filling  the  globe,  closing  both 
cocks,  and  expanding  the  mercury  by  wrapping  a  warm  cloth 
around  the  globe;  globules  of  mercury  will  be  forced  out  at 
the  point  where  the  leak  exists.  By  exhausting  the  globe  and 
at  the  same  time  applying  to  the  leak  semi-melted  beeswax, 
or  a  mixture  of  beeswax  and  tallow,  the  leak  can  be  stopped. 

5.  When  the  globe  is  detached  after  it  has  been  filled, 
every   particle   of   mercury   adhering   to   the   plugs   must   be 
carefully  removed  by  jarring  or  brushing.      This  precaution 
is  very  important.      The  mercury  that  thus  adheres  at  differ- 
ent trials  varies;  therefore  the  accuracy  of  the  weight  taken  is 
sensibly  affected  if  care  is  not  taken  to  remove  all  traces  of 
mercury   outside   of   the   cocks.      For   the    same  reason   any 
globules  of  mercury  adhering  to  the  globe  and  its  connections 
should  be  removed  by  brushing  before  weighing.      In  testing 
fine-grained    powder    both    plugs  should  be  unscrewed  and, 


DENSIMETRY. 

with  the  globe,   carefully   wiped   out  after  each  trial;   with 
ordinary  cannon-powder  this  need  be  done  only  occasionally. 

6.  Whenever  the   upper    part  of  the  barometer-tube  or 
globe  becomes  coated  with  sulphuret  of  mercury  it  should  be 
dismounted  and  washed  with  aqua  regia.      Should  the  upper 
part  of  the  barometer-tube  be  broken,  expose  the  metallic 
socket  which  holds  the  lower  end  to  the  flame  of  a  lamp  until 
the  cement  softens,  remove  the  broken  tube  and  replace  the 
socket.     Coat   the   end  of  the  new  tube  with  cement,   and 
insert  it  in  the  socket  before  the  mixture  cools,  being  careful 
that  the  tube  stands  vertical,  and  attach  it  to  the  scale. 

7.  The  following  precautions  are  necessary  in  using  the 
air-pump:  Always  keep  the  piston-rod  and  piston  well  oiled; 
keep  the  stop-cocks  and  connections  air-tight;   screw  down 
the  vacuum-gauge  before  beginning  to  exhaust;   examine  the 
hose  connections  from  time  to  time.     To  determine  whether 
the  pump  is  tight  and  in  working  order,  close  the  cock  under 
the  bell-glass  table   and    exhaust.       The  vacuum-gauge   will 
show  whether  air  is  admitted,  and  the  leak  may  be  located 
by  the  hissing  sound  made  by  the  air  rushing  in. 

8.  The  following  precautions  are  to  be  observed  in  using 
the  balance:  Always  lower  the  beam  before  putting  the  globe 
or  the  estimated  counterbalancing  weights  on  the  pans,  and 
also  before  removing  either  of  them.     The  small  weights  may 
be  added  or  changed  with  the  beam  in  action.     Always  place 
the  heavier  weights  in  the  centre  of  the  pans  so  as  to  avoid 
any  tendency  to  swing  the  beam  laterally.      In  throwing  the 
beam  into  action,  use  a  gentle  regular  motion.      The  oscilla- 
tions  when    the    balance    is    nearly   in    equilibrium   may   be 
checked   by   gently   lowering  the  beam   and  pans  into  their 
rests  until  the  motion  ceases.      When  again  raised,  the  beam 
will   be  quite  steady,   and   exact   equilibrium  will   be   easily 
established. 

The  Process  of  Determining  the  Density  of  a  Sample 
of  Powder. — The  connections  of  the  instrument  having  been 
previously  tested  and  everything  found  in  working  order,  the 
globe,  with  the  nozzle  attached,  is  carefully  brushed  and 


128  LECTURES   ON  EXPLOSIVES. 

connected  to  the  upper  part  of  the  barometer-tube.  The 
bowl  containing  the  mercury  is  raised  by  means  of  the  elevat- 
ing-screw, until  the  tip  of  the  nozzle  is  immersed  to  a  suffi- 
cient depth  to  prevent  any  air  getting  into  the  globe.  The 
lower  stop-cock  is  closed,  all  the  others  are  opened,  and  the 
air  is  exhausted  from  the  globe  and  tube  by  means  of  the  air- 
pump.  As  soon  as  a  perfect  (or  nearly  perfect)  vacuum  is 
obtained,  as  shown  by  the  vacuum-gauge,  the  lower  stop-cock 
is  opened. 

The  mercury  immediately  rises  into  the  globe,  and,  as  the 
level  of  the  mercury  in  the  bowl  falls,  great  care  must  be 
taken  to  keep  the  tip  of  the  nozzle  constantly  immersed  to  a 
uniform  depth  by  means  of  the  elevating-screw.  As  soon  as 
the  column  of  mercury  becomes  stationary  (it  should  rise  in 
an  unbroken  column  to  about  the  usual  barometric  height), 
the  lower  stop-cock  is  closed.  Air  is  then  admitted  to  the 
top  of  the  tube  by  opening  the  stop-cock  attached  to  the 
catch-bottle,  which  will  cause  a  very  slight  fall  in  the  mercury 
column.  The  other  stop-cocks  of  the  globe  and  tube  are 
then  closed,  the  globe  carefullly  disconnected,  placed  in  its 
seat  on  the  table,  the  nozzle  removed,  and  all  traces  of  adher- 
ing mercury  jarred  and  brushed  off.  The  glebe  filled  with 
mercury  is  then  very  carefully  weighed  and  the  weight  noted 
(W).  The  globe  is  next  emptied,  the  mercury  being  returned 
to  the  bowl,  and  the  upper  plug  of  the  globe  removed  so  that 
the  sample  of  the  powder  can  be  introduced. 

For  many  practical  reasons  it  has  been  found  convenient 
to  use  a  constant,  uniform  weight  of  powder,  the  weight 
adopted  at  this  school  being  9  ounces,  or  3937.5  grains.  The 
sample,  carefully  weighed,  is  introduced  into  the  globe,  the 
nozzle  attached,  and  the  globe  again  connected  with  the  rest 
of  the  instrument.  The  cock  at  the  lower  end  of  the  upper 
part  of  the  tube  is  opened  to  allow  the  mercury  remaining  in 
it  to  escape,  the  catch-bottle  and  nozzle  stop-cocks  closed, 
and  the  air  is  again  exhausted. 

The  mercury  is  run  into  the  globe  and  up  to  the  same 
point  in  the  tube  as  before,  the  cock  closed,  air  admitted,  and 


DENSIME  TR  Y.  1 29 

the  globe  disconnected,  cleaned  and  weighed  as  before.  This 
weight  (W)  is  also  noted.  As  during  the  experiment  the 
temperature  of  the  mercury  has  varied  (due  to  the  rapid 
manipulation),  its  temperature  should  be  determined  at  the 
beginning  of  the  experiment  and  after  each  weighing,  and  the 
mean  of  the  three  thermometric  readings  taken  as  the  true 
temperature,  corresponding  to  which  the  specific  gravity  of 
the  mercury  is  to  be  taken  in  the  subsequent  calculation. 
From  the  data  thus  obtained  the  density  of  the  powder  is 
readily  obtained  from  the  proportion 

D\d\\  W-(W  -  w):  w, 
or 

D  X  iv 

~-  w-  (W'  -  w)' 

in  which  D  =  the   density  of   the   mercury  corresponding  to 

the  temperature  noted; 

d  =  the  density  of  the  powder  to  be  determined; 
W=  the  weight   of  the   globe   filled  with   mercury 

alone; 
W  =  the  weight  of  the  globe  filled  with  mercury  and 

powder; 
w  —  the  weight  of  the  sample  of  powder  taken. 

Evidently  W  —  w  represents  the  weight  of  mercury, 
globe,  and  powder  less  the  weight  of  powder  taken,  and 
W—  (W'  —  w)  the  weight  of  mercury  displaced  by  the 
powder. 

It  is  very  important  in  these  experiments  that  the  mer- 
cury should  be  of  the  proper  quality,  and  in  addition  to 
straining  it  through  chamois-skin  from  time  to  time,  to  remove 
any  impurities,  its  specific  gravity  should  be  tested.  At 
66°  F.,  or  1 8°. 9  C.,  it  should  have  a  specific  gravity  of 

I3.55055. 

The  Dupont  Densimeter. — For  the  determination  of  the 
density  of  large-grained  powders,  the  instrument  in  use  at  the 


13°  LECTURES   ON  EXPLOSIVES. 

Artillery  School  was  constructed  according  to  the  plan  of  one 
designed  by  the  Dupont  Powder  Company,  and  employed  by 
them  with  very  satisfactory  results  at  their  works  near  Wil- 
mington, Del. 

It  is  a  mercury  densimeter,  adapted,  by  its  construction, 
o  the  reception  of  large  grains,  and  having  capacity  for  five 
Kinds  of  powder,  which,  for  convenience,  is  the  weight  of 
Miiple  always  employed.  It  differs,  however,  from  the 
Miiall  densimeter  just  described  by  a  combination  of  the 
different  parts  such  that  the  reservoir  for  holding  the  powder 
and  mercury  to  be  weighed,  and  the  balance  by  means  of 
which  the  weighings  are  made,  are  assembled  together  in  one 
instrument.  The  balance  also  is  so  adapted  to  its  special 
purpose  as  to  simplify  considerably  the  subsequent  process  of 
calculation. 

A  great  saving  of  time  and  labor  is  gained  by  this  form  of 
instrument,  and  the  occurrence  of  breaks  and  leaks,  so  fre- 
quent in  the  small  apparatus,  is  in  a  great  measure  avoided. 

The  instrument  is  enclosed  in  a  case  about  seven  feet  long 
by  two  feet  wide  and  six  feet  high,  built  upon  a  solid  brick 
support,  access  to  the  instrument  being  had  through  double 
doors  which,  when  open,  expose  one  entire  side. 

The  instrument  consists  essentially  of  three  parts,  viz.,  a 
beam-scale,  a  reservoir  to  contain  the  powder  and  mercury  to 
be  weighed,  and  a  bowl  to  contain  the  mercury  when  not 
required  in  the  reservoir. 

The  beam-scale  is  suspended  from  a  hook  firmly  secured  to 

the  top  of  the  case,  and  its  axis  of  suspension  is  a  knife-edge 

lying  in  the  same  plane  with  the  axis  of  suspension  of  the 

reservoir  and  of  the  rods  to  which  are  attached  the  platforms 

-\\    which    the   weights   are   placed.     The   latter    consists    of 

sounds,  tenths  of  a  pound,  and  five-hundredths  of  a  pound, 

marked  with  reference  to  the  weights  they  will  balance  in  the 

-cservoir,     and    of    a   large    unmarked    weight,    termed    the 

counterpoise. 

This  counterpoise  has  a  cavity  bored  in  it  lengthwise,  the 
use  of  which  will  appear  hereafter;  its  weight  is  about  eight 


D  EN  SI  ME  TRY.  1 3  x 

pounds.  The  long  arm  of  the  beam  is  also  graduated,  and  by 
means  of  a  "  rider  "  the  weighings  can  be  made  to  hundredths 
and  thousandths  of  a  pound;  the  graduated  edge  of  the  beam 
is  in  the  same  plane  with  the  knife-edges.  Attached  to  the 
upper  edge  of  the  beam  are  two  small  counterpoises  which 
admit  of  movements  parallel  and  perpendicular  to  the  beam 
respectively,  the  movements  being  regulated  by  screw-spindles 
passing  through  the  counterpoises.  The  one  having  the 
parallel  or  horizontal  motion  is  just  over  the  axis  of  suspension 
of  the  beam,  and  is  used  to  adjust  the  arms  to  the  same 
weight ;  the  other,  having  the  perpendicular  or  vertical  motion, 
is  attached  to  the  shorter  arm,  and  its  function  is  to  regulate 
the  sensibility  of  the  balance.  The  beam  and  its  appurte- 
nances are  of  brass. 

The  reservoir  is  of  cast  iron,  and  consists  of  two  conical 
ends  which  screw  into  a  cylindrical  section.  These  joints  are 
fitted  most  accurately,  lest  ledges  should  be  formed  within  the 
reservoir  which  might  serve  to  retain  enough  mercury  to 
affect  the  weighings.  Attached  to  the  top  of  the  reservoir  is 
a  small  detachable  glass  vase  into  which  the  mercury  rises 
when  the  reservoir  is  filled,  and  which  enables  the  operator  to 
mark  the  exact  point  to  which  it  must  be  filled  for  any  given 
experiment.  A  nozzle,  fitted  with  an  air-tight  stop-cockz 
screws  into  the  lower  conical  section. 

The  reservoir  swings  on  trunnions,  the  beds  for  which  are 
at  the  lower  extremities  of  a  yoke  attached  to  the  beam. 
The  upper  part  of  the  yoke  is  fitted  with  a  vertical  pivot,  by 
means  of  which,  in  addition  to  a  vertical  or  up-and-down 
motion,  the  reservoir  may  be  given  a  horizontal  angular 
movement. 

The  powder  is  introduced  into  the  reservoir  through  a 
circular  mouth  about  2^  inches  in  diameter  in  the  upper  coni- 
cal section. 

A  screw-cap,  fitted  with  a  soft  leather  washer,  covers  the 
mouth,  and  when  removed,  for  the  purpose  of  introducing 
the  powder,  is  hung  on  a  hook  attached  to  the  right-hand  side 
of  the  yoke,  so  as  to  be  included  in  the  weighing.  The  mer- 


132  LECTURES   ON  EXPLOSIVES. 

cury  is  admitted  to  the  reservoir  and  withdrawn  through  the 
nozzle  already  mentioned. 

The  capacity  of  the  reservoir  is  about  78  pounds  of  mercury 
alone,  or  40  pounds  of  mercury  and  5  pounds  of  powder. 
The  reservoir  itself  weighs  20^  pounds. 

The  bowl  is  also  of  cast  iron,  and  has  a  capacity  for  about 
no  pounds  of  mercury.  By  means  of  an  elevating-screw, 
worked  by  a  wheel,  it  can  be  raised  or  lowered  so  as  to  keep 
the  tip  of  the  nozzle  always  immersed  at  a  uniform  depth. 
Near  the  bottom  of  the  bowl,  and  to  one  side,  is  an  outlet- 
pipe,  by  means  of  which  the  mercury  can  be  withdrawn  when 
the  instrument  is  not  in  use. 

In  connection  with  this  densimeter  is  used  an  ordinary 
Ritchie  air-pump,  in  which,  the  cylinder  remaining  stationary, 
the  oscillation  takes  place  in  the  connecting-rod,  which  com- 
municates the  motion  of  the  handle  to  the  piston.  The  air- 
pump  and  densimeter  are  connected  through  a  catch-bottle  by 
means  of  rubber  hose. 

Precautions  to  be  Observed  in  Using  the  Dupont  Den- 
simeter.— After  the  instrument  has  once  been  put  in  thor- 
oughly good  working  order,  serious  injury  to  it  can  result 
only  from  very  rough  treatment.  However  it  is  well  to 
observe  the  following  precautions: 

1.  In  removing  the  reservoir  from  the  yoke,  disconnect 
the  rubber  hose  from  the  glass  vase,  revolve  the  reservoir  on 
its  trunnions  until  it  is  inclined  about  30°  from  the  vertical, 
and  then  raise  it  obliquely  and  very  gently,  so  as  to  avoid  any 
jar  or  shock  upon  the  knife-edges  of  the  beam.     To  replace 
it,  be  equally  careful. 

2.  When  removed  in  order  to  brush  the  globules  of  mer- 
cury,  place  the   reservoir  on  a  table  so   that  it  rests  on  its 
sides,    and,    having   taken   off  the  screw-cap,  brush  out   the 
interior  carefully,  inverting  the  reservoir  to  allow  the  mercury 
to  run  out.     A  slight  jar  will  free  the  nozzle  from  any  parti- 
cles of  adhering  mercuty.      Always  examine  the  screw-threads 
on  the  cap,  as  a  few  globules  of  mercury  always  find  their 
way  into  them. 


DEN  SI  ME  TRY.  133 

3.  The  joint  between  the  glass  vase  and  the  metal  top  of 
the  reservoir  is  very  delicate  and  difficult  to  keep  perfectly 
air-tight.     Therefore  be  particularly  careful  not  to  strike  the 
vase,   or   jar    it   in    any   manner,    especially  in   removing  or 
replacing   the    rubber  hose.     The   latter  should    always    be 
brought  from  the  catch-bottle  over  the   hook  to  which  the 
beam  is  attached. 

4.  It  is  not  necessary  to  use  force  to  make  the  screw-cap 
joint  air-tight,  provided  the  leather  washer  is  not  worn  out. 
The  exercise  of  a  very  gentle  pressure  on  the  wrench  is  suffi- 
cient. 

5.  When  running  the  mercury  into  the  reservoir,  keep  the 
nozzle  immersed  at  such  a  constant  uniform  depth  as  to  pre- 
vent any  air  from  getting  into  the  instrument.     As  it  will  be 
found  necessary  to  continue  to  exhaust  the  air  until  the  mer- 
cury has  risen  to  the  proper  level,  care  should  be  taken  to 
work  the  brake  with  uniform  strokes  so  that  the  flow  of  mer- 
cury may  be  regular. 

6.  The   process   of  weighing  is   often   a  very   important 
operation  on  account  of  the  extreme  sensibility  of  the  beam- 
scale.     As  there  is  no  way  of  arresting  the  vibrations  except 
by  the  hand,  when  equilibrium  is  nearly  produced,  it  is  con- 
venient to  arrest  the  vibrations  by  holding  the  thumb  and 
forefinger  of  the  right  hand  a  little  below  and  above  the  sup- 
port  for  weights  attached  to  the   longer  (right)  arm  of  the 
beam,  while  with  the  left  hand  the  "  rider"  is  manipulated 
until  equilibrium  is  produced. 

7.  The  precautions  necessary  for  the  proper  care  of  the 
air-pump  have  already  been  enumerated.      To  preserve  the 
reservoir  from  rust  while  the  instrument  is  not  in  use,  it  is 
covered  with  a  light  coat  of  paraffin,  which  can  be  readily 
removed  by  holding  it  over  a  flame. 

To  Determine  the  Density  of  Powder  with  the  Dupont 
Densimeter. — The  reservoir  having  been  carefully  cleaned 
and  placed  in  the  yoke,  the  beam  is  accurately  balanced  by 
means  of  the  counterpoise  used  for  that  purpose,  and  the 
eight-pound  counterpoise  placed  on  the  left-hand  support. 


134  LECTURES   ON  EXPLOSIVES. 

The  bowl  is  then  filled  with  mercury  and  run  up  by  means  of 
the  elevating-screw  until  the  tip  of  the  nozzle  is  immersed  to 
the  proper  depth.  The  densimeter  is  then  connected  with 
the  air-pump,  the  nozzle  stop-cock  closed,  and  the  air 
exhausted  by  the  air-pump. 

As  soon  as  the  gauge  indicates  a  vacuum,  the  stop-cock  is 
opened  and  the  mercury  rises  in  the  reservoir,  the  air-pump 
in  the  meantime  being  worked  constantly  and  uniformly. 
When  the  mercury  column  reaches  the  proper  height  in  the 
vase  the  stop-cock  is  closed,  the  hose  disconnected,  and  the 
point  at  which  the  mercury  stands  marked  by  a  wire  used  for 
the  purpose.  (When  the  hose  is  disconnected,  it  sometimes 
happens  that  the  mercury  column  falls  too  low  to  be  marked 
by  the  wire;  in  this  case  a  little  mercury  is  poured  into  the 
tube  from  the  top,  and  the  point  marked  as  before.  Occa- 
sionally a  little  mercury  has  to  be  run  off,  which  can  be  done 
by  carefully  opening  the  stop-cock  until  the  mark  is  reached.) 

The  balance  of  the  beam  is  now  restored  by  dropping 
small  shot  into  the  cavity  of  the  counterpoise,  the  weight  of 
the  latter  being  slightly  less  than  the  reservoir  when  filled 
with  mercury  alone;  this  having  been  done,  the  stop-cock  is 
opened  and  the  reservoir  emptied. 

The  reservoir  is  removed  from  the  yoke,  the  screw-cap 
taken  off,  and  all  particles  of  mercury  carefully  brushed  and 
jarred  out;  it  is  then  replaced  in  the  yoke,  the  cap  hung  on 
the  hook,  and,  the  large  counterpoise  having  been  removed, 
the  equilibrium  of  the  beam  is  verified. 

The  five-pound  weight  is  now  placed  upon  the  left-hand 
support,  and  the  sample  of  powder  introduced  into  the 
reservoir  until  equilibrium  is  again  restored. 

The  screw-cap  is  then  replaced,  the  large  counterpoise 
added  to  the  five-pound  weight  already  on  the  left-hand  sup- 
port, and  the  reservoir  filled  with  mercury,  by  means  of  the 
air-pump,  to  the  same  height  as  before.  The  rubber  hose  is 
again  disconnected  from  the  vase,  and  equilbirium  for  the 
fourth  time  restored  by  placing  weights  on  the  right-hand 
platform  (attached  to  the  longer  arm  of  the  beam),  and,  in 


D  ENSIME  TRY.  135 

addition,  by  manipulating  the  "  rider  "  on  the  beam  if  neces- 
sary. The  sum  of  these  weights  is  the  weight  of  the  mercury 
displaced  by  the  powder,  or  of  a  volume  of  mercury  equal  to 
the  volume  of  the  powder,  and  the  specific  gravity,  or  density, 
of  the  latter  results  from  the  well-established  principle  that 
' '  the  specific  gravities  of  two  substances  are  proportional  to  the 
weights  of  equal  volumes  of  those  substances. 

As  the  density  of  mercury  varies  with  its  temperature, 
and  this  temperature  varies  during  each  experiment,  it  is 
necessary  to  determine  the  temperature  of  the  mercury  at  the 
beginning  of  the  experiment  and  each  time  that  the  reservoir 
is  emptied,  and  the  mean  of  the  thermometric  readings  taken 
as  the  temperature  corresponding  to  which  the  specific  gravity, 
or  density,  of  the  mercury  is  to  be  taken  in  the  subsequent 
calculations. 

Thus  if  D  =  the  density  of  the  mercury  corresponding  to 

the  observed  temperature; 

d  =  the  density  of  the  powder  to  be  determined; 
W  =  the  sum  of  the  weights  on>the  longer  arm; 
w  =  the  weight  of  the  powder, — 

then,  according  to  the  principle  enunciated, 

D  :  d  : :  W  :  w, 
or 

d-  DW 

uw 

In  this  densimeter  not  only  are  the  weighings  rapidly  and 
accurately  made,  but  the  actual  weights  required  for  the  com- 
putation are  obtained  directly  by  a  process  peculiar  to  tiitv 
balance. 

The  weights  for  the  longer  arm  are  marked  double  then 
actual  value  in  reference  to  the  reservoir,  so  that  in  computing 
the  density  of  any  sample  of  powder  it  is  only  necessary  to 
place  the  decimal  point  in  the  value  of  D  one  place  farther 
to  the  right,  and  divide  by  the  value  of  W,  as  indicated  on  the 


136  LECTURES   ON  EXPLOSIVES. 

weights,  which  is  evidently  the  same  thing  as  multiplying  both 

terms  of  the  fraction  -777  by  2,  w  always  being  5  pounds. 

On  account  of  the  considerable  bulk  of  the  sample  em- 
ployed, and  the  comparatively  large  weights  of  powder  and 
mercury  that  consequently  enter  into  the  formula,  very  close 
weighing  with  this  instrument  is  not  absolutely  requisite.  For 
instance,  a  variation  of  46  grains  in  the  actual  value  of  w 
affects  the  resulting  density  of  the  sample  by  only  two  points 
in  the  third  place  of  decimals.  This  feature  is  one  of  great 
practical  utility,  as  it  enables  us  to  dispense  with  very  small 
weights,  and  to  abridge  considerably  the  operation  of  weigh- 
ing. 

Gravimetric  Density  of  Gunpowder. — Before  the  almost 
universal  introduction  of  breech-loading  rifled  guns,  the  gravi- 
metric density  of  gunpowder  was  considered  to  exercise  a 
great  influence  upon  its  ballistic  value.  But  even  then  the 
importance  of  this  property  was  greatly  overrated,  and  at 
present  it  is  of  no  practical  value  whatever,  except  in  connec- 
tion with  muzzle-loading  guns. 

Owing  to  the  terms  in  which  it  has  been  defined,  very  in- 
accurate and  even  erroneous  ideas  exist  as  to  what  is  meant 
by  gravimetric  density. 

In  the  Report  of  the  Chief  of  Ordnance  for  1879,  ^  'ls 
defined  as  "  the  weight  of  a  given  measured  quantity,"  and 
to  this  is  added:  "it  is  usually  expressed  by  the  weight  of  a 
cubic  foot  in  ounces." 

Major  Makinlay,  of  the  Royal  Artillery,  gives  a  better 
idea  of  what  is  meant  by  gravimetric  density,  but  unfortu- 
nately confounds  it  with  the  air-space  of  the  powder  chamber, 
of  which  it  is  approximately  a  measure.  According  to  the 
Woolwich  Text-book,  "  the  gravimetric  density  of  a  charge 
of  powder  in  the  chamber  of  a  gun  is  the  ratio  of  its  weight 
to  the  weight  of  that  volume  of  water  which  would  fill  the 
space  behind  the  projectile  in  the  gun.  It  is  the  mean  density 
of  the  grains  of  powder  and  of  all  the  interstitial  and  other 
spaces." 


DEN  SIM E  TRY.  137 

It  has  been  further  defined  as  "the  weight  of  a  standard 
volume  of  the  powder,  not  pressed  together  except  by  its  own 
weight."  (Ingalls.)  None  of  these  definitions  appear  to  me 
to  be  satisfactory. 

It  is  hardly  necessary  to  say  that  the  gravimetric  density 
of  gunpowder  is  entirely  distinct  from  its  absolute  density,  or 
specific  gravity;  in  fact  it  bears  no  relation  thereto,  as  will 
become  apparent  subsequently,  when  we  shall  find  that, 
according  to  the  "gravimeter, "  an  unusually  dense  powder 
may  be  made  to  appear  much  lighter  than  a  powder  of  very 
low  specific  gravity. 

In  its  general  acceptation,  the  word  " density  "  suggests 
a  comparison,  and  is  almost  universally  represented  by  an 
abstract  number,  which  is  the  result  of  a  ratio.  This  is  so 
well  known  that,  except  for  the  errors  referred  to,  the  state- 
ment would  be  considered  superfluous.  I  can  discover  no 
good  reason  for  discarding  the  idea,  and  would  therefore 
define  gravimetric  density  as  the  ratio  which  the  weight  of  a 
given  volume  of  the  substance,  including  air  and  other  inter- 
stitial spaces,  bears  to  the  weight  of  an  equal  volume  of  the 
standard  taken  at  15°. 5  C.  and  760  mm. 

As  in  the  case  of  absolute  density  there  must  be  a  stand- 
ard to  which  this  ratio  is  referred.  The  standard  originally 
adopted  in  this  country,  and  which  is  still  retained,  is  the 
weight  in  ounces  of  one  cubic  foot  of  distilled  water  at  the 
standard  temperature  (assumed  to  be  1000  ounces). 

Since  the  specifications  furnished  by  the  U.  S.  Ordnance 
Department  for  the  supply  of  service  powders  are  expressed 
in  terms  of  this  standard,  for  practical  reasons  it  will  be 
adopted  in  our  work. 

To  determine  the  gravimetric  density  of  any  powder,  then, 
it  is  only  necessary  to  fill  the  "  gravimeter  "  (  a  copper  meas- 
ure having  a  capacity  of  one  cubic  foot)  and  weigh  it. 

Hence  if  we  represent  by  W  the  weight  in  ounces  of  one 
cubic  foot  of  the  sample,  and  by  D'  the  gravimetric  density, 

W 
1000  :   W  ::  I  :  D'  =  — -, 

1000 


138  LECTURES   ON  EXPLOSIVES. 

It  is  evident  that  the  gravimetric  density  of  the  powder  would 
be  unity  when  one  cubic  foot  of  it  weighed  exactly  1000 
ounces. 

As  before  stated,  from  the  gravimetric  density  of  a  sample 
of  powder  an  approximately  correct  idea  can  be  formed  as  to 
the  volume  of  air-space  in  a  given  charge.  The  air-space  is 
dependent  upon  the  size  and  shape  of  the  granules,  and  the 
amount  of  settling  and  shaking  to  which  the  powder  is  sub- 
jected ;  therefore,  in  determining  the  air-space,  the  percentages 
are  calculated  for  the  powder,  both  loose  and  settled. 

Knowing  the  specific  gravity,  or  absolute  density,  of  the 
powder  under  examination,  as  determined  by  the  densimeter, 
the  air-space  is  found  as  follows: 

Let  D  represent  the  absolute  density  of  the  powder; 
D'  the  gravimetric  density  determined  as  above. 

D' 
Then  -yrwill  be  the  fractional  part,  or  per  cent,  of  the  cubic 

foot  occupied  by  the  powder,  and 

D' 

I  —  -^  the  fractional  part,  or  percent,  of  the  cubic  foot  occu- 
pied by  the  air,  or  the  air-space  in  that  volume. 

The  Dupont  Gravimetric  Balance. — The  apparatus  in 
use  at  the  Artillery  School  was  made  by  H.  Troemner,  of 
Philadelphia,  according  to  designs  furnished  by  Messrs.  E.  I. 
Dupont  de  Nemours  &  Co.,  and  is  used  exclusively  for  the 
determination  of  the  gravimetric  density  of  small-grained 
powders  such  as  is  used  in  muskets,  mortars,  etc.  It  consists 
of  a  small  beam-scale  resting  upon  a  steel  knife-edge,  one  end 
of  which  terminates  in  a  horizontal  Y  which  is  also  fitted  with 
steel  knife-edges  (inverted).  Suspended  from  the  latter  knife- 
edges  by  means  of  steel-faced  trunnions  is  a  vase  having  the 
shape  of  a  truncated  right  cone.  The  vase  has  a  capacity  of 
4500  grains  of  distilled  water,  and  can  be  readily  removed 
from  and  replaced  in  the  Y  during  the  operation.  The  other 
end  of  the  beam  is  graduated  into  100  equal  parts,  which  are 
marked  from  800  to  900  and  are  read  ounces.  Along  the  top 


DEN  SI  ME  TRY.  139 

of  the  beams  slides  a  "  rider"  by  means  of  which  the  gradua- 
tions are  read.  Immediately  below  the  900  mark,  attached 
to  the  under  side  of  the  beam,  is  a  small  hook,  to  which  may 
be  attached  weights,  marked  100  and  200  ounces,  whenever 
necessary. 

To  the  extremity  of  the  graduated  arm  is  attached  a  slid- 
ing weight,  the  use  of  which  will  appear  later.  The  graduated 
arm  moves  between  a  slotted  standard  to  which  is  attached  an 
''arrester"  which  is  manipulated  by  a  milled-head  screw. 
In  addition  to  the  weights  mentioned,  there  is  a  counterpoise, 
marked  4500,  which  is  required  to  produce  equilibrium  in  the 
preliminary  operation  of  adjusting  the  balance.  In  addition 
to  the  balance  proper,  a  hopper,  fitted  with  a  sliding  valve, 
by  means  of  which  the  gunpowder  may  be  introduced  uni- 
formly into  the  vase  during  any  series  of  experiments,  accom- 
panies the  apparatus.  The  instrument  and  its  appurtenances 
are  contained  in  a  wooden  box  about  24"  X  9"  X  9"  to  pro- 
tect it  from  dust  when  not  in  use. 

Precautions  to  be  Observed  in  the  Care  and  Use  of  the 
Dupont  Gravimetric  Balance. — i.  When  not  in  use,  see  that 
the  vase  is  removed  from  the  knife-edges  on  the  Y,  and  placed 
in  the  seat  prepared  for  it  in  the  case. 

2.  In   removing   the  vase   from   its   seat   on   the  Y,  and 
replacing    it,    the    beam    should    invariably   be    arrested,    or 
clamped  by  turning  the  milled-head  screw  to  the  left.     This 
same  precaution  should  also  be  observed  whenever  the  coun- 
terpoise  or  weights  are  placed,  the  one  in  the   vase  or  the 
others  on  the  beam. 

3.  In  producing  equilibrium  by  means  of  the  sliding  weight 
attached  to  the  extremity  of  the  graduated  arm,  unclamp  and 
approximate  by  moving  the  weight  by  hand ;  when  equipoise 
is  nearly  secured,  clamp  the  weight  and  produce  exact  equi- 
librium by  means  of  the  smaller  weight,  which  works  on  the 
screw-thread  projecting  from  the  end  of  the  weight. 

4.  Equilibrium  may  be  produced  in  either  of  two  ways; 
and  should  there  be  no  occasion  for  haste,  it  is  well  to  use  one 
method  as  a  check  upon  the  other. 


14°  LECTURES   ON  EXPLOSIVES. 

First ,  place  the  counterpoise  in  the  vase;  attach  the 
smaller  (100  oz.)  weight  to  the  hook  on  the  under  side  of  the 
beam  and  place  the  "rider"  at  800;  produce  equilibrium  by 
manipulating  the  sliding  weight  as  just  directed. 

Second,  place  the  counterpoise  in  the  vase;  place  the 
"  rider"  at  900,  and  proceed  as  before. 

5.  Before  and  after  using  the  instrument,  carefully  wipe 
and  dust  the  several  parts,  including  the  weights.  And  before 
closing  the  case  see  that  everything  is  in  its  proper  place. 

The  Determination  of  the  Gravimetric  Density  of  Gun- 
powder with  the  Dupont  Gravimetric  Balance. — Place  the 
vase  carefully  upon  the  Y  and  produce  equilibrium  as  above 
directed.  Then  remove  the  vase,  place  it  upon  a  large  sheet 
of  paper  spread  upon  a  table,  and  place  over  it  the  hopper. 
Fill  the  hopper  with  the  powder  to  be  examined,  open  the 
valve  and  allow  the  powder  to  run  into  the  vase  until  it  is  full 
to  overflowing.  Close  the'  valve,  remove  the  hopper  and 
"strike"  the  vase  with  a  straight-edge.  Replace  the  vase 
carefully  upon  the  Y,  and  again  produce  equilibrium  by  means 
of  the  "rider  "  and  weights,  if  necessary. 

From  the  construction  of  the  apparatus  no  calculation  is 
required,  and  it  is  only  necessary  to  note  the  readings  on  the 
arm  and  weight,  and  express  the  sum  decimally. 

Thus,  suppose  that,  to  reproduce  equilibrium  when  the 
vase  filled  with  the  powder  was  placed  upon  the  Y,  it  was 
necessary  to  attach  the  smaller  weight  (marked  100  oz.)  and 
to  place  the  "rider"  at  the  mark  876  on  the  arm;  the  gravi- 
metric density  of  such  a  powder  would  be  written  immediately 
0.976. 

The  Gravimeter. — For  determining  the  gravimetric  den- 
sity of  large-grained  powders,  a  copper  vessel  having  the 
capacity  of  one  cubic  foot  and  called  the  gravimeter  is  used 
in  connection  with  the  balance  already  described  with  the 
densimeter.  Attached  to  the  left  arm  of  the  beam-scale  of 
that  balance  at  the  point  from  whch  the  scale-pan  is  suspended 
is  a  hook,  the  use  of  which  will  appear  later.  The  gravimeter 


DEN  SI  ME  rfR  Y.  141 

is  fitted  with  handles  at  the  opposite  extremities  of  a  diameter 
and  rests  upon  a  cradle,  by  means  of  which  the  powder  may 
be  settled  without  breaking  the  grains  by  subjecting  them  to 
sudden  jars  or  shocks. 

The  cradle  consists  of  a  stout  frame  made  of  oak,  about 
three  feet  square.  Into  the  parallel  upper  frame-pieces  are 
set  two  metal  bearings  which  receive  the  trunnions  attached 
to  the  seat  upon  which  the  gravimeter  is  placed.  All  motion 
of  the  seat  may  be  arrested  by  means  of  stay-pins.  This  is 
necessary  whenever  it  is  desired  to  take  the  gravimetric  den- 
sity with  the  powder  loose.  Uniformity  in  filling  the  gravi- 
meter is  secured  by  placing  a  heavy  glass  plate  across  the  top 
of  the  vessel  and  noticing  whether  the  granules  touch  the 
surface  of  the  glass  throughout.  The  only  precautions  to  be 
observed  in  using  the  gravimeter  are  those  which  refer  to  the 
balance  and  have  already  been  enumerated. 

How  to  Use  the  Gravimeter. — First  carefully  dust  the 
gravimeter  within  and  without,  and  also  the  scale-pans  of  the 
balance;  place  the  gravimeter  on  the  right-hand  pan,  and 
attach  the  counterpoise  to  the  hook  on  the  left-hand  arm. 
Throw  the  beam  into  action,  and  produce  equilibrium,  using 
particles  of  tin-foil  for  the  purpose  if  necessary.  Having 
secured  equilibrium,  throw  the  beam  out  of  action,  remove 
the  gravimeter  and  place  it  upon  the  cradle.  Fill  the  gravi- 
meter loosely,  allowing  the  granules  to  settle  by  their  own 
weight,  and  verifying  the  full  measure  by  applying  the  glass 
plate  to  the  top. 

With  an  assistant  replace  the  gravimeter  thus  filled  upon 
the  balance,  and  reproduce  equilibrium,  using  for  this  purpose 
the  weights  which  accompany  the  balance.  Note  the  sum  of 
the  weights,  and  divide  by  1000;  the  result  will  be  the  gravi- 
metric density  of  the  powder  taken  loose.  Throw  the  beam 
out  of  action,  remove  the  gravimeter  from  the  balance  and 
replace  it  upon  the  cradle.  Withdraw  the  "stay-pins,"  and 
rock  the  gravimeter  until  the  powder  ceases  to  settle,  keeping 
the  vessel  filled  to  the  top  by  introducing  additional  powder 


142  LEC7'URES   ON  EXPLOSIVES. 

from  time  to  time.  Apply  the  glass  plate  as  before,  and 
when  evenly  full  replace  the  gravimeter  upon  the  balance, 
and  reproduce  equilibrium.  The  sum  of  these  last  weights 
divided  by  IOOO  will  be  the  gravimetric  density  of  the  powder 
taken  settled. 


LECTURE   VIII. 

THE    CHEMICAL    THEORY    OF   THE   COMBUSTION   OF   GUN- 
POWDER. 

UNTIL  comparatively  recent  years  the  equation 
2KN03  +  3C  +  S  =  KaS  +  3COa  +  N3 

was  accepted  as  expressing  the  chemical  theory  of  the  decom- 
position of  gunpowder  resulting  from  its  explosion  in  the  bore 
of  a  gun.  But  the  results  of  the  investigations  of  Noble  and 
Abel  have  shown  that  this  reaction  is  far  too  simple,  and  that, 
in  addition  to  the  few  products  obtained  as  represented  in  the 
above  equation,  much  more  numerous  and  far  more  complex 
products  result  from  the  explosion  of  gunpowder.  For  in- 
stance, the  following  substances  have  been  found  among  the 
solid  products :  potassium  carbonate,  sulphate,  sulphide, 
hyposulphate,  and  sulphocyanate,  ammonium  carbonate,  and 
sometimes  free  sulphur  and  carbon;  while  among  the  gaseous 
products  have  appeared  carbon  monoxide  and  dioxide,  nitro- 
gen, hydrogen,  hydrogen  sulphide,  and  marsh-gas. 

Noble  and  Abel's  Calculations. — This  complexity  of 
results  led  Noble  and  Abel,  after  the  closest  investigation  and 
exhaustive  experiments,  to  the  conclusion  that  "  One  and  the 
same  description  of  powder,  exploded  several  times  in  succes- 
sion, will  yield  the  products  of  combustion,  in  the  different 
experiments,  in  variable  proportions;  hence  the  metamor- 
phosis of  gunpowder  cannot  be  represented  by  a  chemical 
equation." 

Berthelot  differed  in  opinion  from  these  investigators,  and 
arrived  at  a  different  conclusion. 

143 


144  LECTURES   ON  EXPLOSIVES. 

He  assumed  that  the  composition  of  the  Waltham  Abbey 
powders  was  represented  as  follows: 

2KN03  +  3C  +  S, 
which  requires  for  100  parts  of  powder: 

Saltpetre 74. 8 

Carbon ." .    13.3 

Sulphur 11.9 

Analysis  of  these  powders  gave: 

Saltpetre 73.55  to  75.04 

Carbon 10.67  "    12.12 

Sulphur 9-93"    10.27 

Berthelot's  Theory. — The  following  theory  was  invented 
by  Berthelot  to  explain  the  remarkable  results  of  Noble  and 
Abel  which  led  to  the  still  more  remarkable  conclusion  given 
above.  Among  the  products  of  explosion  enumerated, 
potassium  hyposulphite  is  not  a  primary  product  of  the  explo- 
sion, but  is  formed  during  the  analysis  of  the  powder  residue; 
while  the  combined  weights  of  potassium  sulphocyanate, 
ammonium  carbonate,  hydrogen,  and  marsh-gas  amount  to 
only  about  1.5  per  cent  and,  as  they  originate  from  secondary 
reactions,  may  be  neglected.  There  still  remains,  however, 
potassium  carbonate,  sulphate,  sulphide,  carbon  monoxide 
and  dioxide,  the  formation  of  which  must  be  accounted  for 
by  any  satisfactory  theory  as  to  the  decomposition  of  a  mix- 
ture of  saltpetre,  carbon,  and  sulphur. 

According  to  Berthelot's  ingenious  theory,  if  we  select 
two  from  several  experiments  of  Noble  and  Abel,  viz.,  one  in 
which  the  maximum  amount  of  potassium  carbonate  and  the 
minimum  of  sulphate  were  produced,  and  another  which 
yielded  the  largest  quantity  of  potassium  sulphate  and  the 
smallest  of  the  carbonate,  then  the  explosion  in  the  first  case 
may  be  represented  by  three  equations: 


COMBUSTION  OF  GUNPOWDER:    CHEMICAL    THEORY.      1  45 

One  third  of  the  powder  would  be  transformed   according 
to  the  equation 


S=K,S+3C01+N1;     .....     (i) 

one  //^//"according  to 

2KNOi  +  3C+S=KaCOi  +  CO,  +  CO  +  Ni  +  S;    .     (2) 

and  one  sixth  according  to 

3C+S=K9COi  +  i.sCO.  +  o.sC  +  S  +  N,.    (3) 


In  the  second  case,  with  a  maximum  of  potassium  sulphate, 
one  third  of  the  powder  would  be  transformed  according  to 
equation  (i);  about  one  half  according  to  equation  (3);  one 
eight  Ji  according  to 

2KN03  +  3C  +  S  =  K,S04  +  2CO  +  C  +  N2;    .     (4) 
and  one  twelfth  according  to 

2KNOS  +  3C  +  S  =  K3SO.+  C03+C,  +  N,.    .     (5) 

Between  the  limits  marked  by  these  two  cases  are  con- 
tained all  the  experimental  results  of  Noble  and  Abel.  If, 
therefore,  we  assume  that,  in  a  given  experiment,  one  portion 
of  the  powder  used  burnt  according  to  the  equations  of  the 
first,  and  the  rest  according  to  those  of  the  second  case,  the 
calculated  results  will  agree  with  those  observed.  And  if  the 
proportions  of  powder,  which  are  transformed  according  to  the 
one  or  other  system  of  equations,  be  changed  from  experi- 
ment to  experiment,  the  quantities  of  the  products  of  com- 
bustion obtained  in  each  experiment  can  be  calculated  in  a 
satisfactory  manner. 

M.  Berthelot  justifies  his  assumption  that  during  explosion 
one  portion  of  the  powder  is  transformed  according  to  one 
and  another  portion  according  to  another  equation  or  system 
of  equations,  by  a  further  assumption  that  the  local  conditions 


146  LECTURES   ON  EXPLOSIVES. 

in.  a.  mass  of  burning  powder  are  not  the  same  in  all  parts,  and 
that  the  cooling  is  too  rapid  to  allow  the  products  to  assume 
a  state  of  chemical  equilibrium. 

This  theory,  however,  does  not  agree  with  experience, 
since,  according  to  it,  considerable  amounts  of  carbon  ought 
to  be  left  free  at  the  end  of  each  explosion,  while  in  twenty- 
eight  experiments  of  Noble  and  Abel  no  free  carbon  was  left, 
and  in  only  three  cases  have  small  insignificant  quantities 
escaped  combustion. 

Debus'  Theory. — Discarding  the  theory  of  the  English 
investigators,  and  taking  exception  to  the  reasoning  of  Ber- 
thelot,  Dr.  Debus  undertakes  to  point  out  the  various  sources 
of  error  in  Noble  and  Abel's  methods,  and,  after  applying  the 
necessary  corrections,  deduces  an  equation  which  he  claims  to 
represent  the  metamorphosis  of  the  powders  of  Waltham 
Abbey. 

This  equation,  deduced  from  the  3 1  experiments  published 
by  Noble  and  Abel,  is 

i6KNO3  +  I.34N  +  21.350  +  I.34H  +  6.638 

=  4.98K2C03  +  13.  i3C02  +  o.84S  +  o.9oK2SO4 

+  3.23CO  +  o.6;SH2  +  2.  ioK2S2  +  17.341*.  .     (I) 

The  first  member  of  the  equation,  representing  the  con- 
stituents of  the  powder,  has  been  calculated  from  the  products 
of  explosion.  The  same  constituents,  as  found  by  the  direct 
analysis  of  the  powders,  are  represented  as  follows: 

i6KNO3  +  21.  i8C  +  6.638, 

which  agree  very  closely  with  those  deduced  from  the  products 
of  explosion.  Powders  of  this  composition,  burnt  according 
to  the  method  of  Noble  and  Abel,  will  form  the  products  of 
explosion  in  quantities  as  represented  in  equation  (I),  if  the 
small  quantities  of  secondary  products  arising  from  the  pres- 
ence of  hydrogen  in  charcoal,  such  as  marsh-gas,  ammonia, 
and  free  hydrogen,  are  neglected. 

The  sulphuretted  hydrogen  is  either  the  product  of  the 


COMBUSTION  OF  GUNPOWDER:     CHEMICAL    THEORY.      147 

direct  union  of  hydrogen  and  sulphur  at  comparatively  low 
temperatures,  or  of  the  action  of  carbonic  acid  and  water  upon 
potassium  sulphide.  In  either  case  its  foundation  has  no 
direct  connection  with  the  explosion,  and  it  ought  to  be  like- 
wise omitted  from  an  equation  representing  the  metamorphosis 
of  gunpowder. 

0.84  atom  of  sulphur  is  represented  as  free,  because  there 
are  no  data  to  show  how  much  sulphur  has  united  with  the 
iron  of  the  apparatus.  It  is  usual  to  represent  the  potassium 
sulphide  as  monosulphide,  while,  as  a  matter  of  fact,  the 
disulphide  is  produced.  Hence  we  may  substitute  for  equa- 
tion (I)  a  much  simpler  one,  as  follows: 


i6KNO3  +  2iC+  58 
=  5K.CO,  +  I3CO,  +  KaS04  +  3CO  +  2K2S2  +  8Na.    (II) 

(The  difference  between  equations  (I)  and  (II)  is  due  to  the 
union  of  the  sulphur  with  hydrogen  and  iron.) 

This  equation  (II)  expresses  only  the  quantitative  relations 
between  the  powder  constituents  and  the  products  of  explo- 
sion; the  reactions  which  occur  during  explosion,  which  of 
them  are  simultaneous,  and  the  order  in  which  they  succeed 
each  other  have  still  to  be  determined. 

It  may  be  assumed  that,  at  first,  all  the  potassium  of  the 
saltpetre  forms  with  carbon  and'oxygen  potassium  carbonate, 
and  that  in  another  stage  sulphur  acts  on  the  potassium  car- 
bonate and  produces  the  mixture  known  as  the  solid-powder 
residue.  Or  it  may  be  assumed  that  potassium  sulphate  is 
the  first  product,  and  that  this  is  afterwards  reduced  by  car- 
bon to  potassium  bisulphide  and  carbonate.  Both  assumptions 
would  lead  to  the  same  results. 

For  an  explanation  of  the  formation  of  potassium  sulphate 
and  carbonate,  carbonic  acid  and  oxide,  and  nitrogen,  Dr. 
Debus  examines  the  results  of  Karolyi's  experiments,  accord- 
ing to  whose  investigations  these  substances  formed  the  chief 
products  of  explosion  of  gunpowder. 

The  equation  deduced  to  represent  the  metamorphosis  of 


148  LECTURES   ON  EXPLOSIVES. 

the  Austrian  powders  experimented   may  be  written  as  fol- 
lows: 

I6KNO.+.I3.C+  5S 

=  3KaC03  +  5KaS04  +  9C03  +  CO  +  8N2.      (Ill) 

From  a  consideration  of  these  two  equations  (II  and  III) 
Dr.  Debus  arrives  at  the  first  general  conclusion  as  to  the 
decomposition  of  gunpowder,  as  follows: 

"  The  combustion  of  gunpowder  consists  of  two  distinct 
stages:  a  process  of  oxidation,  which  is  finished  in  a  very 
short  time,  occupying  only  a  very  small  fraction  of  a  second, 
and  causing  the  explosion,  and  during  which  potassium  car- 
bonate and  sulphate,  carbonic  acid,  some  carbonic  oxide  and 
nitrogen  are  produced,  and  a  process  of  reduction,  which  suc- 
ceeds the  process  of  oxidation  and  requires  a  comparatively 
long  time  for  its  completion. 

"  As  the  oxygen  of  the  saltpetre  is  not  sufficient  to  oxi- 
dize all  the  carbon  to  carbonic  acid,  and  all  the  sulphur  to 
sulphuric  acid,  a  portion  of  the  carbon  and  a  portion  of  the 
sulphur  are  left  free  at  the  end  of  the  process  of  oxidation. 
The  carbon  so  left  free  reduces,  during  the  second  stage  of 
the  combustion,  potassic  sulphate,  and  the  free  sulphur 
decomposes  potassic  carbonate.  Hydrogen  and  marsh-gas, 
which  are  formed  by  the  action  of  heat  upon  charcoal,  like- 
wise reduce  potassic  sulphate,  and  some  hydrogen  combines 
with  suphur,  forming  sulphuretted  hydrogen." 

Accepting  this  view,  equation  (III)  may  be  assumed  to 
represent  the  first,  and  equation  (II)  the  second  stage  of  the 
combustion  of  gunpowder.  If,  moreover,  the  combustion  of 
ordinary  service  powder  takes  place  during  the  first  stage 
according  to  equation  (III),  nearly  the  maximum  quantity  of 
heat  is  obtained  which  a  mixture  of  saltpetre,  sulphur,  and 
carbon  can  produce. 

This  equation  also  corresponds  to  the  most  simple  relation 
of  the  heat  of  formation  of  the  principal  products,  and  also 
requires  the  most  simple  distribution  of  the  oxygen  of  the 


COMBUSTION  OF  GUNPOWDER:    CHEMICAL    THEORY.      149 

decomposed  saltpetre.  If  the  combustion  of  a  mixture  of 
saltpetre,  carbon,  and  sulphur  is  to  produce  potassium  car- 
bonate and  sulphate,  carbonic  acid,  and  nitrogen,  and  if  the 
oxygen  of  the  first  three  products  is  to  stand  to  the  oxygen 
of  the  other  in  the  most  simple  ratios  possible,  then  the  mix- 
ture must  burn  according  to  an  equation  the  proportions  of 
which  so  nearly  approach  those  of  equation  (III)  that  the  latter 
equation  may,  without  sensible  error,  be  assumed  to  fulfil  all 
of  the  foregoing  conditions. 

The  investigator  next  considers  the  error  arising  from 
assuming  that  monosulphide  of  potassium  is  formed  during 
the  combustion  of  gunpowder,  and,  from  an  examination  of 
the  results  obtained  by  Berzelius  and  Mitscherlich,  Noble  and 
Abel,  and  others,  shows  that,  as  a  matter  of  fact,  potassium 
disulphide  is  produced. 

From  these  facts  he  concludes  that  the  second  stage  of 
the  combustion  of  gunpowder  takes  place  according  to  the 
equations 


.    (IV) 
4K,SO.  +  7C  -=  2K,C03  +  2.KS.  +  SCO,.    .      (V) 

The  possibility  of  dissociation  requires  the  additional 
equation 

K,CO,  +  K.S,  +  O,  =  3K,SO.  +  CO,.     .     .    (VI) 

The  final  results  of  the  reactions  represented  by  the  fore- 
going equations  may  be  expressed  by  one  equation,  as 
follows: 

Let  x  represent  the  number  of  molecules  of  saltpetre, 
y         "  "          "        "  atoms          "  carbon, 

z          "  "          "        "        "  "  sulphur, 

molecules  of  carbonic  oxide, 


<  i 


( i 


formed   by  the   combustion   of  such  a  powder  (x,  y,  z  being 
positive  numbers). 

The  general   equation   representing    the   qualitative    and 
quantitative  relations  between  the  constituents  of  the  powder 


LECTURES   ON  EXPLOSIVES. 

on  the  one  hand  and  the  products  of  complete  combustion  on 
the  other  will  then  be 

-  1 6*  - 
tf 
12*  _ 

.  (VII) 

By  means  of  this  equation,  we  can  calculate,  from  that 
portion  of  the  powder  which  produces  the  chief  products,  the 
quantities  of  these  products  formed  during  complete  combus- 
tion. It  would  be  well  just  here  to  classify  the  products  of 
combustion  as  follows: 

1.  Chief  products:  K2CO3,  K2SO4,  K2S2,  CO2,  CO,  and  Na. 

2.  By-products:  H2,  SH2,  CH4,  NH8,  HaO,  and  KCNS. 

3.  Constituents  of  powder  not  burnt:  KNO3,  C,  and  S. 

According  to  what  has  already  been  presented,  the  meta- 
morphosis of  gunpowder  may  be  assumed  to  take  place  in  a 
shell  or  in  the  bore  of  a  gun  as  follows: 

In  the  first  moments  after  ignition,  during  the  explosion, 
powders  of  different  composition  burn  according  to  equation 
(III),  and  in  the  case  of  a  shell  which  will  burst  almost  imme- 
diately and  its  contents  be  scattered  about  no  further  change 
takes  place.  In  the  bore  of  a  gun  the  gases  expand,  move 
the  shot,  and  by  the  performance  of  this  work  lose  a  portion 
of  their  energy;  the  products  of  the  first  stage  of  the  meta- 
morphosis, potassic  carbonate  and  sulphate,  remain  at  a  red 
heat,  in  a  fluid  condition,  for  a  longer  time  in  contact  with 
free  carbon  and  sulphur,  and  produce,  according  to  equations 
(IV)  and  (V),  an  additional  quantity  of  carbonic  acid. 

This  carbonic  acid,  which  is  generated  during  the  move- 
ment of  the  shot  in  the  bore,  prevents  the  too-rapid  diminu- 
tion of  the  tension  of  the  gases;  the  heat  of  the  solid  products 
is,  in  part,  transformed  into  vis  viva  of  the  gas-molecules. 

If  the  gun  were  long  enough  and  the  quantities  of  carbon 
and  sulphur  not  too  large,  every  atom  of  the  former  might  be 
oxidized  by  the  oxygen  of  the  potassium  sulphate,  and  the 


COMBUSTION  OF  GUNPOWDER:    CHEMICAL    THEORY.      1$! 

entire  amount  of  the  sulphur  be  converted  into  potassium 
disulphide  and  sulphate  by  contact  with  potassium  carbonate. 
But  in  reality  this  second  stage  is  never  complete;  the  shot 
will  have  left  the  bore  before  the  termination  of  these  com- 
paratively slow  reactions. 

Recapitulation.  —  i  .  The  mean  composition  of  the  Waltham 
Abbey  powders  can  be  represented  as  follows: 


A  powder  of  this  composition  is  transformed  in  Noble  and 
Abel's  apparatus  according  to  the  equation 


i6KNO3  +  2iC+  58 

=  5K2C08+K2S04+2K2S2 

The  residue  of  the  sulphur,  1.63  atoms,  unites  partly  with 
hydrogen,  partly  with  the  iron  of  the  apparatus. 

2.  The  ordinary  service  and  sporting  powders  contain  for 
every  16  molecules  of  saltpetre  from  13  to  22  atoms  of  carbon 
and  from  5.5  to  8.7  atoms  of  sulphur. 

3.  A   powder   composed   of  pure   carbon,    saltpetre,    and 
sulphur  furnishes  by  its  complete  combustion  potassium  car- 
bonate,  sulphate,   and   disulphide,   carbonic  acid  and  oxide, 
and  nitrogen  as  chief  products. 

4.  An  increase   of   pressure  appears,    cceteris  paribus,    to 
diminish  the  amount  of  carbonic  oxide,  and  in  consequence, 
according    to    equation  (VII),  to    increase   the   quantities   of 
potassium  carbonate  and   disulphide,  and  carbonic  acid,  and 
to  diminish  that  of  potassium  sulphate. 

5.  The    combustion    of    gunpowder    takes   place    in    two 
stages,  one  succeeding  the  other: 

(a)  A  process  of  oxidation  during  which  potassium  sul- 

phate and  carbonate,  carbonic  acid,  and  nitrogen, 
and  perhaps  some  carbonic  oxide,  but  no 
potassium  disulphide,  are  produced. 

(b)  A  process  of  reduction   during  which  carbon  and 

sulphur  left  free  at  the  end  of  the  first  stage  react 
with  some  of  the  products  formed  during  that 


I$2  LECTURES   ON  EXPLOSIVES. 

stage;  the  free  carbon  reducing  potassium  sul- 
phate, with  formation  of  potassium  disulphide  and 
carbonate,  and  carbonic  acid;  the  free  sulphur 
decomposing  potassium  carbonate  with  the  pro- 
duction of  potassium  disulphide  and  sulphate, 
and  carbonic  acid.  (Equations  IV  and  V.) 
6.  The  first  stage  of  the  combustion,  the  explosion 

proper,    takes   place   with   powders   of   various    compositions 

according  to  the  equation 


ioKN03  +  8C  +  3S:  =  2K3C03  +  sK2SO4  +  6CO,  +  sN2. 

But  as  some  carbonic  oxide  is  probably  produced  at  the 
same  time,  equation  (III)  will  more  nearly  represent  the 
reaction. 

7.  In  the  equation  given  immediately  above,  the  oxygen 
in    the    potassium  carbonate    stands    to    the  oxygen  in    the 
potassium  sulphate  in  the  most  simple  ratios  which  can  exist, 
if  these  substances  are  to  be  produced  by  the  combustion  of 
a  mixture  of  saltpetre,  carbon,  and  sulphur.      In  other  words, 
this  equation  represents  the  most  simple  distribution  of  the 
oxygen  of  the  decomposed  saltpetre  among  the  products  of 
the  first  stage  of  combustion.      The  products  as  represented 
by  equation  (III)  are  very  nearly  in  the  same  proportions  as  in 
the  last  equation  ;  therefore  it  follows  that  the  distribution  of 
the  oxygen  between  potassium  carbonate  and  sulphate,  and 
carbonic  acid,  according  to  equation  (III),  very  nearly  corre- 
sponds to  the  most  simple  possible  distribution, 

8.  Ordinary  gunpowders  contain  more  carbon  and  sulphur 
than  is  required  by  equation  (III).    This  excess  of  carbon  and 
sulphur  is  left  free  at  the  end  of  the  first  stage  of  combustion. 
The  free  carbon  then  acts  according  to  equation  (V),  and  the 
free   sulphur   according   to   equation  (IV),  and  both  together 
form  the  second  stage  of  combustion.      These  reactions  are 
endothermic;  heat  is  not  evolved,  but  consumed;    they  are 
not   of   an    explosive   nature,    and    in    practice  are   probably 
seldom  complete.     The  reactions  in  the  second  stage  increase 
the  volume  of  the  gas   formed   during  the  first   stage  of  the 


COMBUSTION  OF  GUNPOWDER:    CHEMICAL    THEORY.      I  53 

combustion  and  diminish  the  temperature  of  the  products.  A 
portion  of  the  carbonic  oxide  is  formed  during  the  second  stage 
by  the  action  of  free  carbon  or  potassium  disulphide  upon 
carbonic  acid. 

9.   The  reactions  represented  by  equations  (II),  (III),  (IV), 
and  (V)  can  be  expressed  by  one  equation,  as  follows: 


,  +  jC  +  ^S 

4*  +  8*)KfS04 


162  - 


in  which  x,  y,  and  z  are  positive  numbers,  and  represent 
respectively  the  number  of  molecules  of  saltpetre,  the  num- 
ber of  atoms  of  carbon,  and  the  number  of  atoms  of  sulphur 
contained  in  such  a  powder;  while  a  represents  the  number 
of  molecules  of  carbonic  oxide  formed  by  the  combustion  of 
such  a  weight  of  the  powder. 

10.  If  a  mixture  of  saltpetre,  carbon,  and  sulphur  were 
required  which  shall  possess  nearly  the  greatest  energy,  and 
at  the  same  time  contain  the  smallest  amounts  of  carbon  and 
sulphur  compatible  with  this  condition,  theory  would  point 
to  the  mixture 


The  service  powders  of  most  nations  fluctuate  about 


LECTURE   IX. 

EXPLOSIVE   MIXTURES   OF   THE   CHLORATE   CLASS. 

IN  this  class  of  explosive  mixtures  the  chlorates  are  sub- 
stituted for  the  nitrates  as  oxidizing  agents.  Berthelot,  who 
discovered  potassium  chlorate  and  recognized  its  oxidizing 
power,  was  first  to  suggest  its  use  in  the  manufacture  of  ser- 
vice powders,  but  his  own  efforts  and  the  experiments  of 
others  in  this  direction  were  attended  with  so  numerous  and 
serious  accidents  that  investigations  in  this  direction  were 
temporarily  abandoned.  The  danger  attending  the  manipula- 
tion of  chlorated  mixtures  seems  to  be  due  to  the  inherent 
chemical  properties  of  potassium  chlorate,  which  is  the  only 
salt  that  has  been  used  practically.  Potassium  chlorate  has 
already  been  alluded  to.  It  is  a  friable  salt  that  fuses  at 
334°  C.  and  decomposes  regularly  at  352°  C.,  evolving  oxygen 
and  leaving  in  the  first  stages  of  decomposition  a  mixture  of 
perchlorate  and  chloride,  but  finally  only  the  chloride.  The 
decomposition  of  this  salt,  unlike  most  cases  of  decomposition, 
is  attended  with  the  evolution  of  heat,  liberating,  according 
to  Berthelot,  at  the  ordinary  temperature,  1 1  cal.  for  each 
equivalent  of  oxygen  (8,gm.)  fixed,  or  1.4  cal.  per  gramme 
of  oxygen,  or  0.54  cal.  per  gramme  of  KC1O3.  This  evolu- 
tion of  heat  serves  to  increase  the  energy  of  chlorated  explo- 
sives, and  may  be  accounted  for  by  assuming  that  the  heat  of 
decomposition  of  the  chlorate  is  exceeded  by  that  evolved 

154 


EXPLOSIVE   MIXTURES  OF   THE    CHLORATE    CLASS.      155 

during  the  combination  of  potassium  and  chlorine  to  form 
potassium  chloride.  This  heat,  which  is  liberated  at  the 
instant  of  decomposition,  together  with  the  low  specific  heats 
of  the  combustibles,  also  serves  to  explain  the  extreme  sensi- 
tiveness to  shock  of  the  chlorate  powders.  The  reaction  also 
begins  at  a  lower  temperature  in  the  case  of  chlorates  than 
with  nitrates,  and,  on  account  of  the  higher  temperature  at 
the  beginning  of  the  reaction,  it  i^  propagated  with  corre- 
spondingly increased  rapidity,  hence  the  more  energetic  and 
shattering  effect  of  these  powders. 

Berthelot  further  explains  the  effects  of  chlorate  powders 
on  the  basis  of  dissociation,  as  follows; 

"  The  compounds  formed  by  the  combustion  of  chlorate 
powder  are  all  binary  compounds,  the  simplest  and  most 
stable  of  all,  such  as  potassium  chloride,  carbonic  oxide,  and 
sulphurous  acid.  Such  compounds  will  undergo  dissociation 
at  a  higher  temperature  and  in  a  less  marked  manner  than  the 
more  complex  and  advanced  combinations,  such  as  potassium 
sulphate  and  carbonate,  or  carbonic  acid,  which  are  produced 
by  nitrate  powders.  It  is  for  this  reason  that  the  pressures 
developed  in  the  first  instance  will  be  nearer  the  theoretical 
pressures  with  chlorate  than  with  nitrate  powders,  and  the 
variation  in  the  pressures  produced  during  the  expansion  of 
the  gases  will  be  more  abrupt,  being  less  checked  by  the 
action  of  the  combinations  successively  reproduced  during 
cooling." 

The  explanation,  therefore,  of  the  brusqueness  and  dan- 
gerous sensitiveness  of  chlorate  powders  may  be  summed  up 
as  follows:  The  high  temperature  developed  due  to  the 
quantity  of  heat  liberated,  combined  with  the  relatively  low 
specific  heats  of  the  products  of  combustion;  the  greater 
volume  of  permanent  gases,  due  to,  the  fact  that  potassium 
chlorate  yields  all  of  its  oxygen  for  the  purpose  of  oxidation, 
while  in  case  of  the  nitrate  a  part  of  the  oxygen  is  retained  by 
the  base;*  and  finally  the  formation  of  simpler  compounds, 

.*  This  difference  in  the  oxidizing  power  of  these  two  classes  of  salts  is 


IS6 


LECTURES   ON  EXPLOSIVES. 


involving  dissociation  in  a  less  marked  degree,  so  that  the 
pressures  are  more  extended  in  their  action. 

The  danger  attending  not  only  the  manufacture  of  chlorate 
powders,  but  also  to  be  apprehended  in  the  manipulation  and 
storage  of  the  powders  when  finished,  is  so  great  that  the 
opinions  of  those  who  have  had  to  deal  with  them  may  be 
quoted  by  way  of  emphasis. 

Dr.  Dupre,  F.R.S.,  an  authority  on  the  subject  of  explo- 
sives, says  in  this  connection:  "  Chlorate  of  potassium,  on 
account  of  the  readiness  with  which  it  lends  itself  to  the  pro- 
duction of  powerful  explosives,  offers  a  great  temptation  to 
inventors  of  new  explosives,  and  many  attempts  have  been 
made  to  put  it  to  practical  use,  but  so  far  with  very  limited 
success.  This  is  chiefly  owing  to  two  causes.  In  the  first 
place  chlorate  of  potassium  is  a  very  unstable  compound,  and 
is  liable  to  suffer  decomposition  under  a  variety  of  circum- 
stances, and  under,  comparatively  speaking,  slight  causes, 

TABLE  SHOWING  PERCENTAGE  COMPOSITIONS  OF  NITRATES  AND  CHLORATES. 


KNOg 

NaN03 

NH4.N03 

KC103 

KC104 

K 

•38  67 

o  T   RO 

28  21 

Na 

27  06 

Cl 

28  96 

N 

13.85 

16.46 

3S.OO 

H 

e  OO 

O 

47.48 

56.48 

60.00 

39-15 

46.32 

TABLE  SHOWING  AMOUNT  OF  AVAILABLE  OXYGEN  IN  NITRATES  AND 

CHLORATES. 


KNOg 

NaNOg 

NH4.N03 

KClOg 

KC104 

KC1 

60    85 

CT  68 

K2O 

4^.0^ 

Na2O 

06  47 

H2O 

AZ     O 

N 

17.41 

je  47 

•2C  o 

0 

39.56 

47.06 

2O.  O 

39-15 

46.32 

shown  by  comparing  not  so  much  their  percentage    compositions  as  the 
relative  amounts  of  their  available  oxygen. 


EXPLOSIVE   MIXTURES  OF   THE    CHLORATE    CLASS.      1 57 

chemical  and  mechanical.  All  chlorate  mixtures  are  liable  to 
what  is  termed  spontaneous  ignition,  or  explosion  in  the  pres- 
ence of  a  variety  of  materials,  more  particularly  of  such  as  are 
acid  or  are  liable  to  generate  acid;  and  all  chlorate  mixtures 
are  readily  exploded  by  percussion,  but  more  particularly  by 
combined  friction  and  percussion,  such  as  a  glancing  blow 
which  might  easily  and  would  often  occur  in  charging  a  hole. 

In  the  second  place  there  is  some  evidence  to  show  that 
the  sensitiveness  to  percussion  and  friction  increases  by  keep- 
ing, more  especially  if  the  explosive  is  exposed  to  the  action 
of  moist  and  dry  air  alternately." 

The  increased  sensitiveness  caused  by  keeping  and  ex- 
posure to  moisture  is  probably  due,  in  part  at  least,  to  the 
chlorate  crystallizing  out  into  fine  crystals  on  the  surface  of 
the  mixture. 

Eissler,  on  the  same  subject,  says:  "  It  is  extremely 
doubtful,  from  the  peculiarities  of  this  salt,  if  anybody  will 
ever  overcome  the  obstacles  due  to  its  inherent  chemical 
properties,  which  nature  manifestly  seems  to  have  made 
unconquerable. 

"In  mixing  these  compositions  great  danger  is  attendant, 
and  too  much  circumspection  cannot  be  used.  They  explode 
instantly  on  any  violent  stroke,  very  often  by  friction  alone; 
sometimes  spontaneously,  as  when  in  a  state  of  rest,  and  no 
known  cause  for  their  combustion  can  be  ascertained. 

"  Many  are  deluded  as  to  its  safety  by  so-called  experi- 
ments with  freshly  made  powder.  Manufacturers  of  this 
compound  may  attempt  to  show  its  safety  by  hammering  and 
cutting  it  and  similar  tests;  but  let  the  powder  be  exposed  to 
the  natural  atmospheric  action,  attract  some  moisture  during 
a  damp  foggy  night,  then  get  dry,  and  the  least  friction  or 
blow  will  cause  an  unexpected  explosion." 

To  this  Major  Cundill,  R.A.,  H.  M.'s  Inspector  of 
Explosives,  adds:  "  Without  going  so  far  as  to  say  that  it  is 
impossible  to  manufacture  a  safe  chlorate  mixture,  it  is  a  fact 
that  out  of  many  which  have  been  examined  with  a  view  to 
their  introduction  into  this  country,  not  one  has  yet  been 


I  58  LECTURES   ON  EXPLOSIVES. 

found  to  be  safe  enough  to  be  licensed,  with  the  exception  of 
asphaline.  .  .  . 

"  I  do  not  pretend  to  say  that  powerful  and  valuable  ex- 
plosives may  not  be,  and  have  not  been,  manufactured  with 
chlorate  of  potash  as  their  main  ingredient,  but  I  contend  that, 
though  these  are  fairly  safe  when  used  for  special  purposes 
and  by  experts,  none  have  as  yet  been  brought  to  notice  (with 
the  previously  named  exception)  which  are  suitable  for 
general  use  by  the  mining  population,  and  which  could  be 
relied  upon  not  to  cause  accidents  under  ordinary  conditions 
of  transport,  storage,  and  use." 

The  explosives  resulting  from  the  use  of  the  chlorates 
may,  broadly  speaking,  be  divided  into  two  classes,  those  in 
which  no  particular  attempt  is  made  to  diminish  the  dangerous 
sensibility  of  the  chlorate  mixtures,  and  those  in  which,  by  the 
addition  of  some  diluting  ingredient  or  by  some  special 
mechanical  treatment,  endeavors  are  made  to  diminish  this 
sensibility. 

According  to  Berthelot,  a  powder  in  which  the  nitre  is 
replaced  by  an  equivalent  quantity  of  chlorate  should  have  a 
heat  of  combustion  greater  by  one  half  than  that  of  the  gun- 
powder, and  should  possess  double  the  force. 

The  reaction  resulting  from  such  a  substitution  may  be 
represented  as  follows: 

3KC103  +  2S  +  5C  =  3KC1  +  2S02  +  SCO, 

which  corresponds  fairly  well  to  a  powder  having  the  com- 
position of 

KC1O, 75-00  parts 

S 12.50     " 

C 12.50     " 

Besides  the  erosion  of  the  walls  of  the  gun  by  the  chlorate 
powders,  the  chlorine  sometimes  liberated  after  firing  is 
deleterious  to  those  exposed  to  its  action. 

These  disadvantages,    together   with  those   already   enu 


EXPLOSIVE  MIXTURES  OF   THE    CHLORATE   CLASS.     159 

merated,  are  not  compensated  for  by  the  superior  explosive 
power  of  the  mixtures. 

Several  chlorate  mixtures,  however,  have  been  proposed 
and  patented,  some  of  which  are  given. 

Asphaline.  —  This  substance  consists  of  thoroughly 
cleansed  wheat  or  barley  bran  impregnated  with  potassium 
chlorate  mixed  with  potassium  nitrate  and  sulphate.  Paraffine 
oil,  paraffine,  ozokerite,  and  soap,  or  some  of  these  substances 
may  be  added.  The  mixture  in  commerce  is  colored  pink 
with  fuchsine. 

The  proportions  of  the  several  ingredients  are: 

Potassium  chlorate 54  parts 

Bran 42      " 

Potassium  nitrate,    \  (( 

Potassium  sulphate  ) 

In  reporting  upon  this  powder,  H.  M.'s  Inspectors  of 
Explosives  in  their  Report  for  1890  note  that  two  samples  of 
asphaline  were  examined  which  had  been  kept  in  store  for  a 
number  of  years.  One  of  the  two  was  quite  mouldy.  Never- 
theless both  samples  were  in  good  condition  as  far  as  their 
safety  was  concerned,  and  they  gave  little  or  no  indication  of 
increased  sensitiveness  to  friction  or  percussion  such  as  is 
often  noticed  in  chlorate  mixtures. 

Melland's  Paper  Powder. — The  following  mixture  is 
boiled  for  an  hour  in  79  parts  of  water: 

Potassium  chlorate 9.00  parts 

"  nitrate    4.50      " 

"  ferrocyanide 3.25      " 

"  chromate   0.06     " 

Charcoal 3.25      " 

Starch   0.05      " 

Strips  of  porous  paper  are  then  dipped  into  the  liquor, 
rolled  into  the  form  of  cartridges,  and  dried  at  100°  C.  To 
prevent  their  absorbing  moisture  they  are  given  a  coating  with 


l6o  LECTURES   ON  EXPLOSIVES. 

a  solution  formed  by  dissolving  one  part  of  xyloidine  in 
three  parts  of  acetic  acid  (sp.  gr.  1.04).  This  paper  is  cheap, 
easy  to  make,  and  fairly  safe.  It  does  not  give  off  much  smoke 
or  leave  much  residue,  nor  does  it  erode  the  piece  in  which  it 
is  fired,  while  it  is  more  powerful  than  gunpowder. 

Augendre's  Powder.  —  This  is  also  known  as  White 
German  or  American  Powder,  and  consists  of 

Potassium  chlorate 50  parts 

"          ferrocyanide 25      " 

Cane-sugar 25      " 

The  substances  are  moistened  and  mixed  in  bronzed  mortars 
and  granulated. 

Pohl,  who  submitted  this  powder  to  many  trials,  modified 
the  composition  as  follows: 

Potassium  chlorate 49  parts 

"          ferrocyanide 28      " 

Cane-sugar 23      " 

Being  in  the  proportion  of  three  equivalents  of  the  chlorate 
to  one  of  each  of  the  others.  Pohl  represented  the  products 
of  combustion  of  such  a  powder  as  follows: 

6KC103  +  K4FeCeN6  +  C1SHMOM 
=  N,  +  6CO  +  6C02  +  1 1 H30  +  6KC1  +  4KCN  +  FeC2. 

From  his  calculation  100  grammes  of  the  powder  give 
52.56  grm.  of  solid  products  and  47.44  grm.  of  gas,  which 
has  a  volume  at  o°  and  76  cm.  of  40,680  c.c.,  and  at  the  tem- 
perature of  combustion  (valued  at  2604°,  5  C.)  a  volume  of 
431,162  c.c.  These  conclusions  are  all  in  favor  of  the  white 
powder,  but  they  have  never  been  verified. 

Sixty  parts  by  weight,  or  77.4  by  volume,  are  equivalent 
to  100  parts  of  gunpowder,  and  they  give  but  31.35  parts  of 
solid  residue,  where  100  parts  of  gunpowder,  according  to 
Bunsen  and  Schischkoff,  give  68  parts  Besides,  the  tem- 
perature of  the  resulting  gas  is  not  so  high  for  the  white 


EXPLOSIVE  MIXTURES  OF   THE   CHLORATE   CLASS.     l6l 

powder,  and  hence  a  greater  number  of  shots  may  be  fired 
without  heating  the  piece  excessively.  The  ratio  of  the  tem- 
peratures is  as  0.779  to  *•  But  the  estimation  of  the  tem- 
perature is  based  on  the  hypothesis  held  as  to  the  nature  of 
the  reaction,  and  on  the  calculated  temperature  of  the  reac- 
tion, neither  of  which  has  been  demonstrated  exactly. 

If  the  process  goes  on  precisely  as  Pohl  believes,  it  is 
difficult  to  explain  the  erosive  action  of  this  powder  upon 
guns  from  which  it  is  fired. 

Augendre  and  Pohl  claimed  other  advantages  for  this  pow- 
der, viz.,  it  keeps  perfectly  in  free  air,  inflames  easily  on 
contact  with  a  spark,  can  be  employed  without  being  granu- 
lated, is  simple  to  manufacture,  and  is  inexpensive. 

According  to  Pohl,  the  manipulation  of  this  powder 
presents  absolutely  no  danger  if  the  substances  are  pure  and 
contain  neither  sulphur  nor  carbon,  and  they  cannot  be 
exploded  by  a  blow  of  iron  on  iron  or  by  friction. 

Experience  does  not  confirm  these  assertions.  Several 
instances  of  explosion  are  known  to  have  taken  place  when 
the  materials  were  mixed  with  great  care;  and  a  bottle  filled 
with  the  powder  has  exploded  when  exposed  to  the  sun  in 
summer.  Even  if  the  undoubted  dangers  which  exist  in  the 
use  of  white  powder  were  overcome,  still  the  erosive  action 
which  it  exerts  on  the  gun  would  tend  to  proscribe  it  for  this 
use.  The  erosive  action  of  the  powder  is  most  marked  on 
cast-iron  and  steel  guns,  and  it  has  therefore  been  proposed 
to  limit  its  use  to  bronze  guns  and  to  the  charging  of  shells, 
for  which  it  seems  especially  appropriate.  According  to 
Hudson,  glass  bulbs  filled  with  concentrated  sulphuric  acid  are 
placed  in  the  shells  with  white  powder,  and  the  shock  of 
impact,  when  the  shells  strike  the  object  to  be  destroyed,  is 
sufficient  to  break  the  bulb,  liberating  the  acid,  which  upon 
coming  into  contact  with  the  powder  ignites  it  and  causes 
explosion. 

Dynamogen. — M.  Petry  has  devised  the  following  process 
for  manufacturing  an  explosive  paper,  which  he  calls  dyna- 
mo gen. 


162  LECTURES   ON  EXPLOSIVES. 

He  dissolves  yellow  prussiate  of  potash  in  pure  water,  and 
heats  the  solution  until  it  boils,  when  he  adds  powdered  char- 
coal, stirring  the  mixture  well.  Allowing  this  to  cool,  he 
next  adds  successively  potash,  chlorate  of  potash,  and  starch, 
triturated  in  water. 

The  proportions  are  as  follows: 

Potassium  ferrocyanide 17  parts 

Water 150     " 

Charcoal 17      ' ' 

boiled,  well  stirred,  and  allowed  to  cool;  to  which  are  added 

Potash 35  parts 

Potassium  chlorate  .  . .  = 70     " 

Starch 10     " 

Water 50     " 

The  whole  mixture  is  made  into  a  thin  paste,  and  spread  with 
a  brush  on  ordinary  filtering-paper.  The  paper  is  dried  on  a 
moderately  heated  plate,  and  as  soon  as  one  side  is  thoroughly 
dry  the  other  side  is  varnished  in  a  similar  manner.  Three 
coats  are  given  each  side,  and  the  paper  so  impregnated  is  cut 
up  and  rolled  into  cartridges. 
Hahn's  Powder  consists  of 

Potassium  chlorate   367. 5  parts 

Antimony  tersulphide 168.3      " 

Spermaceti 46.0     " 

Charcoal 18.0     " 

The  last  three  substances  are  thoroughly  mixed,  and  the 
chlorate  added  just  before  the  powder  is  to  be  used,  the  mix- 
ing being  done  by  sieves.  The  addition  of  the  spermaceti  is 
claimed  to  protect  the  mixture  against  explosion  by  friction. 

Horsley's  Powder  consists  of  a  mixture  of  finely  powdered 
potassium  chlorate  and  gall-nuts  in  the  proportions  of  three  to 
one. 

The  powder  may  be  granulated  by  passing  it  through  a 


EXPLOSIVE  MIXTURES   OF   THE   CHLORATE   CLASS.     163 

sieve  while  in  a  damp  state.  The  ungranulated  form  of 
powder  experimented  with  in  Austria  for  use  in  small  arms 
was  not  satisfactory.  The  granulated  powder  is  stated  to 
explode  at  221°  C.,  and  its  force  to  be  five  times  that  of  gun- 
powder. 

Fertilisers  Powder  is  recommended  for  use  mainly  as  a 
detonating  powder,  or  for  filling  bullets  or  shells.  It  has,  in 
the  past,  been  used  in  the  manufacture  of  explosive  bullets, 
It  consists  of 

Potassium  chlorate 2.000  parts 

Sulphur i.ooo     " 

Sporting  gunpowder 0.125      " 

Animal  charcoal 0.020     " 

Parone's  Explosive  consists  of  two  parts  of  potassium 
chlorate  and  one  of  carbon  disulphide. 

From  experiments  in  Italy  with  the  9-cm.  and  15-cm. 
projectiles  it  was  concluded  that  this  mixture  was  an  exceed- 
ingly safe  one;  that  it  would  not  explode  without  a  fuse — not 
always  a  desirable  quality — and  that,  although  its  effects  were 
not  strikingly  superior  to  those  of  gunpowder,  they  increased 
rapidly  with  an  increase  of  calibre. 

Petrofracteur,  a  chlorate  powder  recently  endorsed  by  the 
Austrian  military  committee,  consists  of 

Potassium  chlorate 67  parts 

Nitrobenzene 10     " 

Potassium  nitrate 20     ' l 

Antimony  sulphide 3      ' ' 

As  in  the  case  of  the  nitrates,  so  with  the  chlorates,  the  list 
of  proposed  mixtures  is  well-nigh  unlimited.  By  far  the 
majority  of  these  powders  have  proven  worse  than  useless,  for 
reasons  already  given.  Those  mixtures  intended  for  use  as 
fuse  compositions  are  the  only  ones  that  have  become  of  any 
practical  value. 

Fuse  Compositions. — Of  the  vast  number  of  chlorate 


164  LECTURES   ON  EXPLOSIVES. 

powders  proposed,  only  those  mixtures  intended  for  use  as 
fuse  compositions  have  proven  of  general  value  in  practice. 
Davey's  Fuse  Composition,  which  consists  of 

Potassium  chlorate 6  or  6  parts 

"         nitrate 5  "   3      " 

"         ferrocyanide 2^4      " 

11         bichromate 5  "  —    " 

Antimony  sulphide 5  "   3      " 

Hill's  Fuse  Compositions,  which  were  prepared  by  Mr. 
Hill  while  chemist  to  the  U.  S.  Naval  Torpedo  Corps,  and 
were  designed  for  the  several  systems  of  torpedoes. 

Fuse  Composition  for  the  Contact  System. — This  sys- 
tem requires  a  composition  more  sensitive  than  that  used  in 
either  the  percussion-cap  or  cannon  primer. 

The  following  mixture  proved  satisfactory,  and  is  made  by 
finely  powdering  and  mixing  together,  under  alcohol: 

Potassium  chlorate 60.50  parts 

Antimonious  sulphide 33-5O     " 

Phosphorus  (amorphous).  ...        6.00     " 

Composition  for  Friction  Fuses. — Satisfactory  results 
were  obtained  when  the  following  mixture  was  used  to  explode 
spar  torpedoes: 

Potassium  chlorate 44-44  parts 

Manganic  oxide. 44-45      " 

Phosphorus  (amorphous) 11.11      " 

The  ingredients  must  be  finely  powdered  separately,  mixed 
under  alcohol,  and  used  while  wet. 

The  Sulphuric-acid  Fuse. — This  belongs  to  a  class  of 
fuses  known  as  chemical  fuses.  The  substances  are  separated 
and  kept  apart  until  required  for  action,  when  they  are 
brought  into  contact,  and  unite  chemically  with  the  evolution 
of  heat  and  production  of  flame.  Such  action  occurs  when 


EXPLOSIVE  MIXTURES  OF   THE   CHLORATE   CLASS.     1 65 

sulphuric  acid  is  brought  into  contact  with  a  mixture  of  equal 
parts  of  potassium  chlorate  and  cane-sugar.  When  these 
materials  only  are  used  the  action  of  the  fuse  is  somewhat 
sluggish,  particularly  when  the  fuse  has  been  manufactured 
for  any  length  of  time.  But  if  the  following  ingredients,  in 
the  proportions  given,  be  used,  the  ignition  will  be  instan- 
taneous: 

Potassium  chlorate 41.4  parts 

"          ferrocyanide.    .....    17.2      " 

Cane-sugar 41.4     " 


Composition  Used  in  the  Harvey  Fuse. — The  principle 
of  this  fuse  is  precisely  the  same  as  that  just  described.  The 
sulphuric  acid  reacts  upon  the  following  mixture: 

Potassium  chlorate 17.0  parts 

Cane-sugar 4.5      " 

Nut-galls 1.5      (t 


Composition  for  Fuses  to  be  Exploded  by  Frictional 
Electricity. — The  following  mixture  is  used  in  all  igniters 
made  at  the  U.  S.  Naval  Torpedo  Station  for  use  with  fric- 
tional  machines: 

Potassium  chlorate 45.00  parts 

Antimonious  sulphide 2°-75      " 

Phosphorus  (amorphous) 5.75      " 

Carbon 28.50 


c  < 


The  ingredients  are  finely  powdered  separately,  mixed  under 
alcohol,  and  used  while  wet. 

English  Priming  Material  originally  consisted  of 

Copper  subphosphide 10  parts 

"       subsulphide 45      " 

Potassium  chlorate 45      " 


J66  LECTURES  ON  EXPLOSIVES. 

The  proportions  of  the  ingredients  are  now  varied,  in  order 
to  produce  compositions  of  different  degrees  of  sensitiveness. 
The  ingredients  are  prepared  and  mixed  as  described  above. 
Austrian  Priming  Material  consists  of 

Potassium  chlorate i  part 

Antimony  sulphide i     " 

Plumbago  (powdered) trace 


LECTURE  X. 

CLASSIFICATION   OF   EXPLOSIVE   COMPOUNDS.       EXPLOSIVE 
COMPOUNDS    OF   THE    NITRO-SUBSTITUTION   CLASS. 

THE  explosive  substances  thus  far  treated  of  have  been 
produced  by  mixing  together  mechanically  combustible  sub- 
stances with  oxidizing  salts.  We  shall  now  consider  that 
class  of  explosives  known  as  explosive  compounds,  in  which 
the  oxidizing  agent  is  introduced  chemically  into  the  mole- 
cule, thus  forming  no  longer  a  mixture  but  a  true  chemical 
compound,  each  molecule  of  which  contains  the  oxidizing 
atoms  and  atoms  having  a  strong  affinity  for  oxygen.  It  is 
evident  that  the  relation  existing  between  the  constituents  in 
the  latter  case  must  be  far  more  intimate  than  in  the  former. 

As  has  been  already  stated,  the  chief  explosive  compounds 
are  formed  by  the  action  of  nitric  acid  upon  various  organic 
substances  containing  carbon,  hydrogen,  and  oxygen.  This 
combination  of  the  oxides  of  nitrogen  with  the  hydro- 
carbon groups  may  give  rise  to  two  classes  of  explosive  com- 
pounds, viz : 

Nitro-derivatives  of  the  A  romatic  Series  of  Hydrocarbons* 
or  Nitro-substitution  Compounds,  and 

Nitric-derivatives  from  Alcohols,  or  Nitric  Ethers  and 
Esters. 

Nitro-substitution  Compounds. — This  class  of  substances, 
most  of  which  are  themselves  explosive,  or  enter  as  important 
ingredients  into  a  large  class  of  explosives,  differ  from  nitric 

167 


1 68  LECTURES   ON  EXPLOSIVES. 

ethers  in  that  they  cannot  be  decomposed  by  distinct  reac- 
tions so  as  to  reproduce  the  original  substances  which  com- 
bine to  form  them. 

The  principal  organic  substances  so  far  used  in  connection 
with  explosives  of  this  class  are  the  hydrocarbons  of  the 
aromatic  series. 

As  a  rule,  the  aromatic  compounds  are  richer  in  carbon 
than  the  fatty  compounds,  containing  at  least  six  carbon 
atoms,  and  when  decomposed  by  various  methods  yield  as 
one  of  the  products  benzene.  They  not  infrequently  appear 
as  products  of  vegetable  life,  but  more  frequently  they  are 
obtained  from  coal-tar  by  fractional  distillation. 

When  treated  with  alkalies  nitric  acid  is  not  reproduced, 
but  various  nitrogenous  substances  are  formed,  and  when 
subjected  to  the  action  of  reducing  agents  the  result  is  the 
formation  of  amides, 

As  a  class  the  nitro-compounds  are  less  energetic  in  their 
action  and  more  stable  than  the  nitric  ethers. 

This  is  explained  by  Berthelot  by  the  application  of  the 
principles  of  thermochemistry,  the  loss  of  energy  involved  in 
the  formation  of  this  class  of  explosives  being  considerably 
greater  than  that  entailed  by  the  formation  of  the  nitric 
ethers. 

Thus  in  the  case  of  nitrobenzene  potash,  which  when 
combined  with  dilute  nitric  acid  liberates  only  13.7  Cal., 
cannot  supply  by  a  simple  reaction  the  energy  requisite  to 
reproduce  the  acid  and  benzene,  the  union  of  which,  in  order 
to  form  nitrobenzene,  liberates  36.5  Cal.  In  the  case  of  nitric 
ether  and  nitroglycerine,  however,  only  from  4  to  6  Cal.  are 
necessary  to  reproduce  each  equivalent  of  acid,  so  that  the 
requisite  energy  is  available  for  the  regeneration  of  the  orig- 
inal substances.  The  difference  in  the  molecular  structure  of 
these  two  clases  of  explosives  may  further  serve  to  explain  in 
part  the  greater  intensity  of  action  of  the  nitric  ethers  as  com- 
pared with  nitro-compounds. 

Thus  the  carbon  chain  of  aromatic  hydrocarbons  and  the 
benzene  ring  may  be  represented  as  follows: 


CLASSIFICATION  OF  EXPLOSIVE   COMPOUNDS.         169 

I  H 

I  I 

6x/C\/2  Hv    /C\/H 

^C        Cf  XC        C/ 

II       I  Hi 

/c      cv  /c      c\ 

57  \/  \  H/  \c/  \H 

I  I 

4  H 

Six-carbon  Ring.  Benzene  Ring. 

In  acting  upon  any  member  of  the  aromatic  series  of 
hydrocarbons  with  nitric  acid  in  order  to  form  a  nitro-substi- 
tion  compound,  one  or  more  atoms  of  hydrogen  are  replaced 
by  one  or  more  molecules  of  the  univalent  radical  nitryl  (NO,), 
and  in  this  transfer  the  nitrogen  atom  of  the  nitryl  radical  is 
attached  directly  to  the  carbon  atoms. 

Thus,  by  acting  upon  benzene  with  nitric  acid  to  form 
nitrobenzene,  the  reaction  may  be  represented  as  follows  : 

C.H.  +  HNO,  =  C,H6(NO,)  +  H2O. 

In  the  formation  of  nitrobenzene  one  atom  of  -hydrogen  in 
the  benzene  has  been  displaced,  and  one  molecule  of  the 
univalent  radical  nitryl  (NO,)  has  been  substituted  therefor. 
This  transfer  may  be  shown  in  the  structural  formula  for  ben- 
zene, thus: 


/C\   /H 


H 


/C 
/ 


H 


Nitrobenzene—  C8H3.  NOa. 


I7O  LECTURES  ON  EXPLOSIVES. 

in  which  the  nitrogen  atom  of  the  nitryl  molecule  is  connected 
directly  to  the  carbon  atom  of  the  benzene  chain.  In  the 
case  of  nitric  ethers  we  shall  see  that  the  nitryl  molecule  is 
not  directly  connected  with  the  carbon  atom,  but  through 
the  interposition  of  an  atom  of  oxygen,  which  serves  to 
separate  the  several  atoms  of  the  explosive  molecule  hav- 
ing the  greater  affinities  for  each  other,  so  that,  upon  the  de- 
composition of  the  molecule,  these  atoms,  having  a  greater 
distance  to  traverse  before  they  can  combine,  acquire  a  cor- 
respondingly increased  momentum,  thereby  causing  greater 
interatomic  activity  and  energy,  which  results  in  correspond- 
ingly increased  intensity  of  action. 

It  is  readily  seen  that  when  only  one  atom  of  hydrogen  is 
replaced  in  the  benzene  chain,  the  resulting  product  must  be 
the  same  irrespective  of  which  particular  atom  is  replaced 
(since  they  all  bear  the  same  relation  to  the  carbon  atoms  to 
which  they  are  attached),  or  by  what  method  the  change  is 
accomplished. 

This,  however,  is  not  the  case  when  two  or  more  atoms 
of  hydrogen  are  replaced,  since  it  is  found  that  such  multiple 
replacement  gives  rise  to  the  formation  of  isomeric  com- 
pounds, which,  in  the  case  of  explosives  as  in  other  prod- 
ucts, possess  characteristic  properties,  and  it  is  not  a  violent 
assumption  to  suppose  that  the  stability  of  the  explosive  mole- 
cule may  depend  largely  upon  the  relative  positions  of  the 
atoms  replaced  by  the  nitryl  radical  in  the  aromatic  chain. 

Thus,  by  acting  upon  mono-nitrobenzene  with  concen- 
trated nitric  acid,  a  more  highly  nitrated  product  is  obtained, 
namely,  di-nitrobenzene,  in  which  two  molecules  of  nitryl 
are  substituted  for  two  atoms  of  hydrogen. 

Upon  inspection  it  is  readily  seen  that  there  are  three 
(and  only  three)  separate  and  distinct  positions  that  the  sub- 
stituted molecules  can  assume  in  the  benzene  ring,  thus: 


CLASSIFICATION  OF  EXPLOSIVE   COMPOUNDS.         I?  I 


°SN/° 


I      o 

Hv  /C\  ,N/    Hv  /C\  ,H      H,  /C\ 
\C    C/  ^O    XC    C/         XC    C 

II  I  II  I  II  I 

yc       cv  /c      cv  ^o       /c       c 

H/  \c/  \H  H/   \c/  \3^          H/    \c/ 

I  I  I 

H  H 

O^ 

(I)  (2)  (3) 

For  purposes  of  explanation  we  may  orient  the  ring, 
beginning  at  the  uppermost  carbon  atom,  and,  proceeding 
around  to  right,  designate  each  atom  by  means  of  a  number, 
thus  : 


6  C          C  2 
5  C         C3 

W 


Although  there  is  but  one  molecular  formula  for  di-nitro- 
benzene  —  C6H4(NO2), — there  may  be  three  structural  or 
graphic  representations  of  this  compound  as  indicated  above, 
and  if  the  theory  of  molecular  structure  be  true,  each  of  these 
compounds  should  possess  certain  characteristic  properties. 
In  support  of  this  theory  note  the  three  isomeric  compounds 
formed  by  substituting  two  molecules  of  hydroxyl  (OH)  for 
two  atoms  of  hydrogen  with  the  formation  of  dioxy-benzene. 
If  in  the  substitution  of  OH  for  H,  in  the  ring,  two  adjacent 
atoms  of  H  (i  and  2,  etc.)  be  replaced,  the  result  is  pyrocate- 
chin ;  if  alternate  atoms  (i  and  3,  etc.)  be  replaced,  the  re- 
sult is  resorcin ;  and,  finally,  if  opposite  atoms  in  the  ring  be 
replaced  (i  and  4,  etc.),  we  have  hydroquinone. 

According  to  the  relative  positions  of  the  replaced  atoms, 


I/2  LECTURES   ON  EXPLOSIVES. 

the  resulting  substitution  products  are  known  as  ortho-,  meta-, 
and/tfrtf-compounds — ortho  when  adjacent  atoms  are  replaced, 
meta  when  alternate,  and  para  when  opposite.  The  replace- 
ment is  .  sometimes  denoted  by  appending  figures  to  the 
common  isomeric  formula  or  name,  thus :  di-nitrobenzene 
(1:2)  is  ortho-dinitrobenzene;  (1:3)  is  meta-dinitrobenzene; 
(1:4)  is  para-dinitrobenzene,  all  having  the  common  formula 
C.H4(NO,),. 

In  the  tri-substitution  derivatives  the  same  principle  ob- 
tains. There  may  be  three  (and  no  more)  compounds  formed 
by  replacing  three  atoms  of  H,  and  if  the  replacement  be  by 
the  same  radical,  the  resulting  substitution  products  will  be 
isomeric,  and,  according  to  the  positions  of  the  replaced 
hydrogen  atoms,  they  are  distinguished  as  adjacent  ( i  :  2  : 3), 
symmmetrical  (1:3:5),  and  asymmetrical  (i  :2  14). 

The  number  of  isomer-derivatives  depends  entirely  upon 
the  replacing  radicals;  thus  by  substituting  the  same  radical 
there  can  be  but  three  isomeric  tetra-substitution  products; 
two  dissimilar  radicals  may  give  20,  three  such  radicals  may 
give  1 6,  while  four  may  give  30  tetra-derivatives. 

Although  it  cannot  be  asserted  absolutely  that  the  stability 
of  the  explosive  molecule  is  dependent  upon  or  regulated  by 
the  position  of  the  replaced  atoms  in  the  ring,  there  is  much 
evidence  to  show  that  it  is  at  least  affected  thereby,  and,  other 
things  being  equal,  the  symmetrical  substitution-derivative  is 
the  most  stable,  as  might  be  expected,  since,  by  the  arrange- 
ment of  its  atoms,  it  would  naturally  require  a  greater  disturb- 
ance to  destroy  the  equilibrium  of  the  molecule.  We  shall 
have  occasion  to  refer  to  this  subject  again  in  connection 
with  the  nitric  derivatives,  nitric  ethers  and  esters. 

Tri-nitro-phenol,  or  Picric  Acid. — One  of  the  best  ex- 
amples of  this  class  of  explosive  compounds  is  Tri-nitro- 
phenol,  or  Picric  Acid,  which  was  discovered  by  Hausmann 
in  1788.  He  made  it  by  treating  indigo  with  nitric  acid.  It 
may  be  obtained  in  various  ways,  but  the  cheapest  and  best 
source  is  from  the  action  of  nitric  acid  on  phenol,  or  "  car- 
bolic acid,"  one  of  the  products  of  the  distillation  of  coal-tar. 


CLASSIFICATION  OF  EXPLOSIVE   COMPOUNDS-         173 

The  reaction  may  be  represented  by  the  following  equation : 
C6H5OH+3HN03-C6H2(NOa)3OH+3H20. 

It  may  be  prepared  experimentally  by  introducing  into 
a  glass  flask  of  iso-c.c.  capacity  about  5-10  c.c.  of  fuming 
nitric  acid,  and  adding  cautiously,  in  very  small  quantities, 
about  1-2  c.c.  of  carbolic  acid.  The  reaction  is  very 
violent,  and  is  attended  with  the  copious  development  of 
nitrous  fumes.  When  the  reaction  has  subsided  and  the 
flask  become  cold,  yellow  crystals  of  picric  acid  will  be  found 
in  the  liquid. 

Picric  acid  is  made  commercially  by  melting  carbolic  acid 
and  mixing  it  with,  strong  sulphuric  acid,  then  diluting  the 
tl  sulpho-carbolic  "  acid  with  water,  and  afterwards  running  it 
slowly  into  a  stone  tank  containing  nitric  acid.  This  is 
allowed  to  cool,  when  the  crude  picric  acid  crystallizes  out, 
the  acid  liquid  (which  contains  practically  no  picric  acid,  but 
only  sulphuric  with  some  nitric  acid)  being  poured  down  the 
drains. 

The  crude  picric  acid,  after  being  drained,  is  transferred  to 
the  "  boiling-stones,"  where  it  is  dissolved  in  water  by  the  aid 
of  steam  and  afterwards  allowed  to  cool,  when  most  of  the 
picric  acid  recrystallizes. 

The  "  mother-liquor"  is  then  transferred  to  the  precipi- 
tating-tank,  in  which  the  picric  acid  still  left  in  solution  is 
precipitated  by  the  addition  of  sulphuric  acid. 

The  picric  acid  left  in  the  "  boiling-stones"  is  once  more 
dissolved  in  hot  water,  and  this  second  solution  is  transferred 
to  the  crystallizing-tank,  where  it  is  left  to  cool,  and  where 
the  picric  acid  again  crystallizes.  Finally,  the  picric  acid, 
after  draining  in  the  tank,  is  transferred  to  a  centrifugal 
machine  to  remove  the  excess  of  moisture,  and  then  dried  on 
glazed  earthenware  trays  in  a  steam-box  in  which  the  temper- 
ature is  not  allowed  to  exceed  100°  F.  According  to  Hill 
and  Abel,  picric  acid  does  not  explode,  but  when  heated  it 
burns  quickly  and  sharply  with  a  bright  flame. 


LECTURES   ON  EXPLOSIVES. 

An  investigation  into  the  subject  of  the  explosiveness  of 
picric  acid,  undertaken  by  Col.  Majendie  and  others,  tends  to 
show  that  picric  acid  could  not  be  exploded  by  heat  even  when 
confined  in  large  masses,  but  it  was  by  no  means  proven  that 
it  could  not,  under  certain  circumstances,  be  exploded  by  the 
action  of  fire. 

Desortiaux  states  that  when  heated  slowly  it  vaporizes 
without  undergoing  any  decomposition,  but  when  heated 
brusquely  to  a  temperature  a  little  above  300°  it  explodes 
with  violence. 

Berthelot  has  also  recently  studied  this  subject,  and  con- 
firms the  view  of  Desortiaux.  He  says:  "  Should  a  nitro- 
compound,  such  as  picric  acid,  while  burning  in  large  masses, 
happen  to  heat  the  sides  of  the  containing  enclosure  to  a  de- 
gree sufficient  to  induce  deflagration,  the  deflagration  might 
combine  to  further  increase  the  temperature  of  the  enclosure, 
and  the  phenomenon  might,  occasionally,  be  transferred  into 
a  detonation.  It  would  even  suffice  that  the  detonation  should 
occur  in  an  isolated  point,  either  during  a  fire,  or  owing  to  the 
local  overheating  of  a  boiler  or  apparatus,  to  enable  it  to  orig- 
inate the  explosive  wave  and  propagate  itself  by  influence 
throughout  the  whole  mass,  causing  a  general  explosion." 

There  exists  no  doubt,  however,  that  picric  acid  is  liable 
to  be  exploded  by  detonation  or  by  a  blow,  and  that  the 
picrates  and  the  mixtures  of  picric  acid,  with  oxidizing  agents, 
are  highly  explosive. 

In  1873  Sprengel  stated  that  "  picric  acid  alone  contains 
a  sufficient  amount  of  available  oxygen  to  render  it,  without 
the  help  or  foreign  oxidizers,  a  powerful  explosive  when  fired 
with  a  detonator.  Its  explosion  is  almost  unaccompanied  by 
smoke." 

Apart  from  the  investigation  above  referred  to,  the  detona- 
tion of  picric  acid  has  recently  attracted  attention  from  the 
alleged  use  of  this  substance  by  the  French  Government  in  a 
particular  fused  and  consolidated  condition,  as  an  explosive, 
under  the  name  of  melinite. 

M.   Eugene    Turpin   has  also  taken   out   a  patent  which 


CLASSIFICATION  OF  EXPLOSIVE   COMPOUNDS.         1?$ 

claims  the  employment  "  as  an  explosive  agent  for  military  or 
other  uses  of  the  tri-nitro-phenol,  or  picric  acid,  of  commerce, 
unmixed  with  any  oxidizing  substance,"  by  the  use  of  a  pow- 
erful fulminate  detonator,  or  by  the  use  of  an  intermediate 
priming  of  picric  acid  in  powder,  primed  by  the  fulminate,  or 
by  dispensing  with  the  fulminate  and  employing  a  sufficiently 
large  charge  of  ordinary  quick-burning  powder  enclosed  in  a 
strong  tube  and  made  to  burst  inside  the  charge  of  picric 
acid. 

The  explosiveness  of  picric  acid  by  detonation  has  been 
investigated  experimentally,  with  the  following  results: 

1st.  Dry  picric  acid  may  be  perfectly  detonated  by  means 
of  a  5 -grain  fulminate  detonator. 

2d.  The  detonation  of  a  small  quantity  of  dry  picric  acid 
is  capable  of  detonating  a  quantity  of  picric  acid  placed  at  a 
short  distance  from  it. 

3d.  The  detonation  of  picric  acid  containing,  at  any  rate, 
as  much  as  17  per  cent  of  water  may  be  effected  by  detonating 
a  charge  of  dry  picric  acid. 

4th.  A  thin  layer  of  cold  picric  acid  will  be  exploded  by  a 
weight  of  54  pounds  falling  20  feet,  and  it  may  be  exploded  by 
one  pound  falling  26  inches.  The  sensitiveness  greatly  in- 
creases with  warming,  so  that  when  heated  to  a  temperature 
just  below  its  melting-point  (about  240°  F.)  a  weight  of  one 
pound  falling  14  inches  will  explode  it. 

Borlinetto's  Powder. — As  far  back  as  1867  Borlinetto 
proposed  a  mixture  of  picric  acid  and  other  oxidizing  agents 
for  blasting  purposes.  The  ingredients  and  the  proportions 
in  which  they  were  to  be  mixed  are  as  follows : 

Picric  acid IO.O  parts 

Sodium  nitrate   10.0       " 

Potassium  chromate 8.5       " 

The  resulting  powder  proved  too  sensitive  to  be  of  prac- 
tical value. 

Many  salts,  known  as  picrates,  have  been  derived  from  pic- 
ric acid,  but  the  only  ones  which  have  been  used  to  any  ex- 


LECTURES   ON  EXPLOSIVES. 


tent  for  explosive  purposes  are  the  salts  of  potassium  and 
ammonium.  All  of  the  picrates,  except  C6H2(NO2)3ONH4 , 
are  readily  exploded  by  heat  or  blows. 

Potassium  Picrate  (C6H2(NO2)3OK).—  This  is  one  of  the 
most  violently  explosive  of  the  picrates.  It  is  made  by  mix- 
ing warm  potassium  carbonate  with  a  boiling  solution  of  picric 
acid  in  water.  On  cooling,  the  liquid  deposits  small  crystal- 
line needles  of  a  golden-yellow  color  which  show  green  and 
red  colors  by  reflected  light.  Heated  gradually  to  310°  C.  it 
explodes  violently ;  and  it  may  also  be  detonated  by  a  sharp 
blow. 

When  mixed  with  oxidizing  agents,  and  especially  potas- 
sium chlorate,  its  explosive  properties  are  very  much  increased. 
Such  a  mixture  approaches  very  nearly  to  nitioglycerine  and 
guncotton  in  violence,  but  it  is  so  sensitive  to  friction  and 
shocks  as  to  be  practically  useless.  When  containing  15  per 
cent  of  moisture,  potassium  picrate  is  safe  from  detonation 
by  blows,  and  ignites  only  locally  on  contact  of  flame. 

Several  mixtures  containing  the  potassium  salt  have  been 
experimented  with,  but  with  no  great  degree  of  success. 

Fontaine's  Powder,  consisting  of  potassium  picrate  and 
chlorate,  was  made  and  tested  in  Paris  as  a  charge  for  shells 
and  torpedoes,  but  it  was  very  dangerous  to  manipulate,  and, 
after  a  terrible  accident  in  1869,  it  was  abandoned. 

Designolle's  Powder. — This  powder  is  made  on  a  large 
scale  at  Le  Bouchet  in  France,  and  is  graded  according  to  the 
proportions  of  the  ingredients,  which  are  potassium  picrate 
and  nitrate,  with  or  without  the  addition  of  charcoal. 

The  compositions  of  the  four  varieties  made  at  this  factory 
are  as  follows: 


Designolle's  Powder. 

Torpedoes  and 
Shells. 

Cannon. 

Small  Arms, 
Muskets,  etc. 

Ordinary 
Calibre. 

Large 
Calibre 

Potassium  picrate           .... 

55 
45 

50 
50 

16.4 
74-4 
9.2 

9.6 

79-7 
10.7 

9  0 
80.0 
IT.O 

28.6 
65.0 
6.4 

22.9 
69.4 

7-7 

Potassium  nitrate 

Charcoal       .  .                   . 

CLASSIFICATION  OF  EXPLOSIVE    COMPOUNDS.         1 77 

These  powders  were  made  according  to  the  ordinary 
processes  followed  in  the  manufacture  of  gunpowder,  from  6 
to  14  per  cent  of  water  being  used,  and  the  trituration  being 
three  hours  for  torpedo-powder,  six  hours  for  musket-,  and 
nine  hours  for  cannon-powder.  The  powder  was  granulated 
as  usual.  The  torpedo-  and  shell-powders  were  tried  at  Brest 
and  Toulon  with  excellent  results.  According  to  Roux  and 
Sarrau,  the  heat  of  combustion  of  the  55  per  cent,  mixture 
will  be  916  cal.,  and  of  the  50  per  cent.  1180  cal. 

The  cannon-  and  musket-powders  were  noted  for  their  uni- 
formity of  action,  the  variations  in  the  initial  velocities  of  the 
projectiles  being  not  more  than  two  metres.  According  to 
Jouglet,  60  grammes  of  Designolle  powder  produced  the  same 
result  as  350  grammes  of  ordinary  powder,  while  the  force  of 
these  mixtures  could  be  varied  between  quite  wide  limits, 
according  to  the  amount  of  picrate  which  they  contained.  In 
spite  of  their  superior  ballistic  properties,  Designolle  powders 
appear  to  be  less  brisant  than  black  powder.  They  give 
scarcely  any  fumes  while  burning,  and  do  not  erode  the  piece 
in  which  they  are  fired. 

The  picrates  constitute  a  series  of  crystalline  bodies  of 
definite  composition  and  known  reactions,  and  there  is  no 
reason  to  apprehend  that  they  may  decompose  "  spon- 
taneously." 

Ammonium  Picrate  (C6H2(NO2)3ONH4)  is  prepared  by 
saturating  warm  picric  acid  with  concentrated  ammonia-water. 
When  neutralization  is  complete  another  charge  of  picric  acid 
is  dissolved  in  the  same  liquid  and  ammonia  again  added. 
The  solution  is  allowed  to  stand  and  cool,  when  the  salt  crys- 
tallizes out  in  transparent  orange-colored  prisms.  It  may  also 
be  obtained  crystallized  in  beautiful  citron-yellow  needles  by 
treating  picric  acid  with  ammonium  carbonate.  According  to 
Hill  and  Abel,  if  flame  is  applied  to  ammonium  carbonate, 
it  burns  without  any  tendency  to  explosion.  It  is  almost 
insensitive  to  blows  or  friction.  According  to  Desortiaux,  it 
explodes  when  heated  to  about  310°  C.,  but  if  heated  in  free 
air  to  a  temperature  below  300°  C.  it  fuses  and  burns. 


LECTURES   ON  EXPLOSIVES. 

Brugere  Powder.  —  This  powder  has  been  made  to  some 
extent  in  France,  and  has  been  found  to  be  stable,  safe  to 
manufacture  and  handle,  but  rather  expensive.  It  consists  of 

Ammonium  picrate  .............  54  parts 

Potassium  nitrate   ...........  46      " 

Heated  to  310°  C.  this  mixture  burns  with  one  half  the 
velocity  of  ordinary  powder.  Its  force  is  about  twice  or  three 
times  that  of  black  powder.  It  is  but  slightly  hygroscopic, 
leaves  but  little  residue  (which  is  not  erosive),  and  gives  off 
a  small  amount  of  inodorous  gas.  Experiments  with  the 
chassepot  showed  that  2.6  grammes  of  this  powder  produced 
the  same  effect  as  5^  grammes  of  regulation  powder. 

Brugere  powder  is  said  to  give  a  velocity  of  more  than 
2000  feet  per  second  with  small  arms,  and  to  cause  very  slight 
recoil.  Large  numbers  of  cartridges  of  this  powder  were 
ordered  for  the  new  Lebel  rifles,  but  it  is  stated  that  a  recent 
examination  of  a  quantity  of  this  ammunition  that  had  been 
stored  at  Chalons  showed  that  the  powder  had  deteriorated  to 
such  an  extent  that  the  whole  lot  had  to  be  condemned. 

Brugere  expresses  the  reaction  produced  by  the  explosion 
as  follows: 


C6H2(N02)3ONH4  +  2KN03  -  5CO2  +  3N2  +  3H2  +  K2CO3. 

Hence  100  grammes  of  the  powder  should  give  69.14 
grammes  of  gaseous  products,  which  at  o°  and  76  cm.  would 
have  a  volume  of  52.05  litres.  A  direct  determination  gave 
48  litres.  Compared  with  the  analogous  results  obtained  by 
Bunsen  and  Schischkoff  for  black  powder,  the  ratio  of  the 
volumes  is  as  2.5  :  I.  It  is  extremely  doubtful,  however, 
whether  a  reaction  (as  above  given)  will  yield  CO2  and  H  at 
the  same  time. 

Abel's  Powder.—  About  the  same  time  that  Brugere 
introduced  his  powder,  Abel  patented  a  similar  powder  in 
England  which  consisted  of  a  mixture  of  ammonium  picrate, 
potassium  nitrate,  and  charcoal.  When  flame  is  applied  to 
particles  of  this  mixture  they  deflagrate  with  a  hissing  sound, 


CLASSIFICATION  OF  EXPLOSIVE   COMPOUNDS.         1 79 

but  the  deflagration  has  but  little  tendency  to  spread  to  the 
contiguous  particles;  but  if  the  mixture  be  strongly  confined, 
as  in  shells,  it  explodes  violently,  and  exerts  a  destructive 
action,  less  powerful  than  that  of  guncotton,  nitroglycerine 
preparations,  and  Designolle  powder,  but  considerably  greater 
than  that  of  gunpowder.  It  is  to  be  remarked  that  while 
ammonium  picrate  and  potassium  nitrate  mixed  in  these  pro- 
portions undergo  mutual  decomposition,  with  the  production 
of  the  highly  deliquescent  salt,  ammonium  nitrate,  yet  if  the 
two  be  dissolved  together  in  water,  the  addition  of  sufficient 
water  to  even  thoroughly  moisten  the  mixture  appears  to 
induce  no  such  change,  since  when  again  dried  the  mixture 
seems  to  have  no  greater  tendency  to  absorb  moisture  from 
the  air.  Indeed  the  powder  is  no  more  hygroscopic  than 
black  powder,  and  appears  to  be  fully  as  stable,  while  the  fact 
that  water  may  be  used  in  incorporating  the  ingredients  with- 
out any  detriment  to  the  final  product  renders  its  manufac- 
ture, at  least,  not  more  dangerous  than  that  of  ordinary 
gunpowder,  and  it  may  be  subjected  to  the  same  processes  of 
pressing  and  granulating  as  are  applied  to  the  latter. 

Shells  charged  with  picric  powder  have  been  fired  in 
England  from  guns  of  different  calibres  up  to  the  9-inch  gun, 
with  a  charge  of  43  pounds  of  R.  L.  G.  powder,  and  without 
an  accident  of  any  kind.  Some  comparative  experiments 
have  also  been  instituted  between  this  powder  and  compressed 
guncotton  in  submarine  mines,  the  results  of  which  indicated 
that  the  destructive  action  of  the  two  was  not  very  different 
when  applied  under  the  pressure  of  water.  For  use  in  large 
submarine  mines  wet  guncotton  is  undoubtedly  more  efficient, 
but  for  use  in  small  offensive  torpedoes  the  granular  form  of 
the  picric  powder  can  be  used  to  great  advantage  in  com- 
pletely filling  the  case. 

Professor  Hill  made  Abel's  powder  as  follows: 

Ammonium  picrate 42. 18  parts 

Potassium  nitrate 53-97     " 

Charcoal  (best  alder) 3.85      " 


LECTURES   ON  EXPLOSIVES. 

These  ingredients  were  moistened  with  water  and  worked 
under  wheels,  granulated,  etc.,  as  in  the  manufacture  of 
ordinary  powder.  Thus  obtained  the  powder  had  a  yellow- 
ish-green color,  was  easily  granulated,  and  no  difficulty  was 
experienced  in  working  it. 

Compared  with  gunpowder  as  to  the  amount  required  as 
a  bursting-charge  for  cast-iron  spherical  shells,  the  force  of 
this  powder  was  found  to  be  to  that  of  gunpowder  as  1.75 
to  I.  It  appeared,  however,  to  burn  imperfectly,  giving  off  a 
heavy  greenish-yellow  smoke,  which  was  supposed  to  be  due 
to  imperfect  working  of  the  mixture  under  the  wheels,  and  to 
too  small  a  proportion  of  KNO3,  as  is  evident  from  an  exam- 
ination of  the  proportions  used. 

As  a  charge  for  fuses  and  igniters  excellent  results  were 
obtained.  As  may  be  inferred  from  what  has  already  been 
said,  nitro-substitution  compounds  may  be  derived  from 
almost  every  substance  rich  in  carbon  and  hydrogen,  but  as 
yet*  very  few  such  compounds  have  become  prominent  except 
those  derived  from  benzole,  napthaline,  etc.,  which  are  now 
being  largely  used  as  important  constituents  of  such  explosives 
as  bellite,  securite,  roburite,  etc. 

Tri-nitro-cresol. — Tri-nitro-cresol  is  similar  to  tri-nitro- 
phenol,  or  picric  acid,  and  may  be  obtained  from  cresol  pre- 
cisely as  picric  acid  is  derived  from  phenol,  or  carbonic  acid; 
that  is,  by  treating  it  with  nitric  acid  and  substituting  for  three 
atoms  of  hydrogen  three  molecules  of  nitryl  (NO,),  with  the 
formation  of  the  nitro-product,  and  three  molecules  of  water, 
thus: 

C7H7.OH  +  3HN03  =  C7H4(N02)3.OH  +  3H,O. 

The  formation  of  isomeric  compounds,  all  of  which  are 
represented  by  the  same  formula — C7H4(NO2)3.OH — during 
the  process  of  nitration,  will  be  referred  to  later. 

Tri-nitro-cresol  crystallizes  in  yellow  needles  which  are 
slightly  soluble  in  cold  water,  but  rather  more  so  in  boiling 
water,  alcohol,  and  ether.  It  melts  at  about  100°  C. 


CLASSIFICATION  OF  EXPLOSIVE   COMPOUNDS.         l8l 

In  France,  tri-nitro-cresol  is  known  as  "Cresilite,"  and, 
mixed  with  melinite,  is  used  for  charging  shells. 

By  neutralizing  by  means  of  concentrated  ammonium 
hydrate  (NH4OH)  a  boiling-hot  saturated  solution  of  tri- 
nitro-cresol,  a  double  salt  of  ammonium  and  nitro-cresol 
crystallizes  out  upon  cooling  which  is  similar  to  ammonium 
picrate.  This  salt  is  known  as  * '  Ecrasite, "  and  has  been 
experimented  with  in  Austria  for  charging  shells.  Ecrasite 
is  a  bright  yellow  solid,  greasy  to  the  touch,  melts  at  100°  C., 
is  unaffected  by  moisture,  heat  or  cold,  ignites  when  brought 
into  contact  with  an  incandescent  body  or  open  flame,  burning 
harmlessly  away  unless  strongly  confined,  and  is  insensitive 
to  friction  or  concussion.  It  is  claimed  to  possess  double  the 
strength  of  ordinary  dynamite,  and  requires  a  special  detonator 
(containing  not  less  than  2  gm.  of  fulminate)  to  provoke  its 
full  force.  Notwithstanding  the  excellent  properties  attrib- 
uted to  this  explosive,  several  imperfectly  explained  and 
unexpected  explosions  that  have  occurred  in  loading  shells 
with  it  have  prevented  its  general  adoption  up  to  the  present 
time. 

Melinite. — For  many  years  the  secret  of  the  composition 
of  this  explosive  was  so  well  guarded  that  nothing  definite 
could  be  learned  about  either  the  character  of  the  ingredients 
or  the  method  of  manufacture.  At  present,  however,  there 
seems  little  doubt  as  to  the  composition  of  the  original 
melinite,  although  the  French  claim  that  the  original  inven- 
tion has  been  so  modified  and  perfected  that  the  melinite  of 
to-day  cannot  be  recognized  in  the  earlier  product. 

As  originally  invented,  melinite  consisted  of  a  mixture  of 
fused  picric  acid  and  tri-nitro-cellulose  dissolved  in  a  mixture 
of  ether  and  alcohol.  Theoretically  the  following  proportions 
were  required,  and  the  process  of  incorporation  is  as  follows: 

Dissolve 

Guncotton 30  parts 

in  a  mixture  of 

Ether 2  parts  ) 

Alcohol. .  .  I  part    j  45  PartS 


1 82  LECTURES   ON  EXPLOSIVES. 

and  to  this  add 

Picric  acid  (fused  and  pulverized)  70  parts 

The  ether-alcohol  mixture  is  allowed  to  evaporate  spon- 
taneously and  the  resulting  cake  is  granulated. 

In  place  of  the  ether-alcohol  mixture,  acetone,  which  is 
equally  efficacious  and  less  expensive,  may  be  used. 

Melinite  possesses  the  characteristic  yellow  color  of  picric 
acid,  has  a  bitter  taste,  is  almost  without  crystalline  appear- 
ance, and  when  ignited  by  a  flame  or  heated  wire  it  burns 
with  a  reddish-yellow  flame,  giving  off  copious  volurries  of 
black  smoke. 

The  earlier  forms  of  melinite  were  very  unstable,  several 
explosions  resulting  both  from  handling  and  during  manufac- 
ture, notably  that  in  the  factory  at  St.  Omer,  France,  which 
destroyed  six  adjacent  factories  and  two  houses.  Within  the 
last  two  years,  however,  the  French  claim  to  have  so  far  per- 
fected the  original  explosive  that  it  is  now  a  perfectly  safe 
explosive  in  manufacture,  handling,  transportation,  and  stor- 
age, but  one  accident  having  occurred  from  its  use  within 
three  years.  Its  present  composition  is  not  definitely  known, 
but  it  is  generally  believed  to  contain  picric  acid  mixed  with 
some  oxidizing  substance.  Its  use  alone  in  shells  has  been 
discontinued,  and,  instead  of  melinite  alone,  about  two  thirds 
of  the  space  within  the  shell  is  filled  with  cresilite.  The  re- 
maining space — one  third — is  then  filled  with  melinite,  which 
is  rammed  in  by  means  of  mallets. 

It  is  claimed  that  no  melinite  shell  has  ever  burst  in  a  gun, 
and  no  accident  has  ever  occurred  in  drawing  the  charges  from 
the  shells.  France  is  reported  to  have  a  full  supply  of  melinite 
shells  ready  for  use  ashore  and  afloat. 

There  seems  to  be  but  little  doubt  that  the  English  explo- 
sive "Lyddite"  is  identical  with  the  original  melinite,  the 
secret  having  been  purchased  by  the  English  Government 
from  M.  Turpin,  the  inventor  of  melinite. 

Mono-nitrobenzene,  or  Nitrobenzene. — This  nitro-com- 


CLASSIFICATION  OF  EXPLOSIVE   COMPOUNDS.         183 

pound  has  already  been  referred  to,  and  in  the  same  connec- 
tion the  principle  upon  which  it  is  made. 

It  was  discovered  by  Mitscherlich  in  1834,  and  is  now 
manufactured  on  a  very  large  scale  for  use  in  the  preparation 
of  aniline.  According  to  the  strength  of  the  acids  used,  the 
resulting  compound  will  be  mono-,  di-,  or  tri-nitrobenzene. 

In  order  to  obtain  the  mono-nitro-compound,  40  parts  of 
HNO3  of  specific  gravity  1.400  is  mixed  with  60  parts  of 
H2SO4  of  specific  gravity  1.840,  and  to  every  three  parts  of 
this  mixture  one  part  of  pure  benzene  is  added.  The  propor- 
tion of  H2SO4  may  be  reduced  to  58$  percent,  that  of  HNO8 
being  raised  to  41^-  per  cent.  On  account  of  the  violence  of 
the  reaction  the  benzene  should  be  added  gradually  to  the 
acid  mixture,  and  also,  on  account  of  the  volatility  of  both 
the  benzene  and  the  nitro-product,  the  temperature  during 
the  process  of  manufacture  should  be  kept  as  low  as  possible. 
This  can  be  accomplished  generally  by  means  of  a  current  of 
water  and,  when  made  in  the  laboratory,  by  agitating  the 
flask  from  time  to  time.  When  the  reaction  is  complete,  the 
nitrobenzene  will  appear  upon  the  surface  of  the  acid  mixture, 
and  may  be  separated  by  drawing  off  the  acids  by  means 
either  of  a  siphon  or  of  a  separatory  funnel.  To  avoid  the 
formation  of  any  of  the  di-nitro-product,  an  excess  of  benzene 
may  be  added,  which  will  be  subsequently  found  mixed  with 
the  nitro-product,  whence  it  may  be  separated  by  fractional 
distillation,  its  boiling-point  being  considerably  lower.  After 
separation  from  the  acids  it  is  thoroughly  washed,  first  in 
water,  and  finally  in  a  weak  alkaline  solution,  in  order  to  free 
it  from  all  traces  of  acidity. 

Nitrobenzene  varies  in  color  from  being  practically  color- 
less to  a  deep  reddish  orange;  it  is  oily  in  appearance,  boils 
between  205°  and  210°  C.,  solidifies  at  3°C.,  and  at  15°  C. 
has  a  specific  gravity  of  1.187.  It  possesses  the  strong 
characteristic  odor  of  "  bitter-almond  oil,"  a  sweet  burning 
taste,  and  is  poisonous  in  both  gaseous  and  liquid  state.  It 
is  but  slightly  soluble  in  water,  but  dissolves  readily  in  alcohol, 
benzene,  and  concentrated  nitric  acid.  In  the  cold  it  dis- 


I 84  LECTURES   ON  EXPLOSIVES. 

solves  nitrocellulose,  reducing  it  to  a  pasty  or  jelly-like  con- 
sistency. In  commerce  it  is  largely  known  as  "  Mirbane 
Oil."  .-.;  ,• 

Nitrobenzene  is  not  in  itself  an  explosive  under  ordinary 
circumstances,  but  when  highly  heated  it  decomposes  with 
the  evolution  of  nitrous  fumes,  and  if  thrown  in  small  quan- 
tities upon  an  iron  plate  or  into  an  iron  vessel  at  a  red  heat 
it  detonates  violently.  Ignited  it  burns  with  a  reddish, 
smoky  flame.  Its  value  as  an  explosive  is  derived  from  mix- 
ing it  with  high  explosives,  such  as  guncotton,  nitroglycerine, 
etc.,  where  it  acts  as  a  deterrent,  either  retarding  or  prevent- 
ing explosion.  When  mixed  in  small  quantities  with  nitro- 
glycerine it  has  been  found  to  lower  the  freezing-point  of  that 
explosive.  When  mixed  with  potassium  chlorate  it  forms 
one  of  the  principal  ingredients  of  "  Rack-a-rock  "  (this 
explosive  will  be  considered  later). 

Di-nitro-benzene.  —  By  acting  upon  benzene  with  the 
strongest  acids  obtainable,  nitric  and  sulphuric,  and  allowing 
the  temperature  during  reaction  to  rise  to  100°  C.,  two  atoms 
of  hydrogen  will  be  replaced  by  two  nitryl  molecules  (of  the 
HNO3)  with  the  formation  of  the  di-nitro-compound. 

On  the  manufacturing  scale,  however,  di-nitrobenzene  is 
prepared  by  renitrating  the  mono-nitro-compound.  This 
method  may  be  reproduced  in  the  laboratory  as  follows: 

Prepare  an  acid  mixture  consisting  of  40  parts  of  nitric 
acid  (sp.  gr  1.500)  and  60  parts  of  sulphuric  acid  (sp.  gr. 
1.845)  and>  without  waiting  for  this  mixture  to  cool,  to  every 
two  parts  add  one  part  of  mono-nitrobenzene.  During  the 
reaction  the  temperature  will  reach  100°  C.,  and  copious 
nitrous  fumes  will  be  evolved  which  should  be  either  con- 
densed, or  discharged  in  the  open  air  by  means  of  a  hood  or 
other  contrivance.  After  the  reaction  ceases,  the  contents  of 
the  flask  should  be  brought  gradually  to  a  state  of  gentle 
ebullition,  and  kept  at  that  temperature  for  ten  or  fifteen 
minutes,  and  then  allowed  to  cool.  The  contents  of  the  flask 
should  next  be  decanted  upon  a  filter,  and  the  solid  residue, 


CLASSIFICATION  OF  EXPLOSIVE   COMPOUNDS.         185 

which  generally  consists  of  a  mixture  of  ortho-,  meta-,  and 
para-di-nitrobenzene,  washed  upon  the  filter  until  all  traces 
of  acidity  disappear. 

Thus  prepared,  di-nitrobenzene  is  a  hard,  crystalline  solid, 
the  crystals  being  long  brilliant  prisms,  varying  in  color  from 
a  light  lemon-yellow  to  about  the  color  of  ordinary  brown 
sugar.  As  already  stated,  the  formula  C6H4(NOa)2  represents 
three  isomeric  compounds,  of  which  the  7;z^/#-derivative  is 
most  abundantly  produced  by  the  method  just  described,  and 
may  be  distinguished  from  the  other  isomers  by  its  melting- 
point;  the  ;^ta-derivative  melting  between  83°  and  89°  C., 
the  ortho-  at  118°  C.,  and  the  para-  at  172°  C. 

Properly  made,  di-nitrobenzene  should  contain  no  traces 
of  the  mono-compound,  and  should  be  odorless.  It  is  soluble 
in  warm  water  and  alcohol,  and,  like  the  mono  compound,  is 
poisonous. 

It  is  not  of  itself  explosive,  and  when  heat  is  applied  to 
it  fuses,  and  gradually  becomes  ignited,  burning  with  a  smoky 
flame.  When  mixed  with  substances  rich  in  oxygen,  and 
especially  when  the  oxygen  is  held  in  feeble  combination,  it 
forms  strong  explosives,  e.g.,  bellite,  securite,  etc. 

Tri-nitrobenzene. — The  tri-nitro-derivative  of  benzene 
may  be  prepared  by  treating  meta-di-nitrobenzene  with  a 
mixture  of  concentrated  nitric  and  Nordhausen  sulphuric 
acids.  It  may  also  be  made  by  decomposing  tri-nitrobenzoic 
acid — C6Ha(NO2)3CO2H — into  carbonic  acid  and  tri-nitroben- 
zene  by  heating  it  to  210°  C.,  its  melting-point. 

Tri-nitrobenzene  has  not  been  used  as  an  explosive  or 
ingredient  of  explosives  until  very  recently,  and  consequently 
very  little  is  known  of  its  properties  as  such.  It  has  been 
proposed  as  a  substitute  for  picric  acid  in  powders  containing 
that  ingredient,  but  it  is  weaker  than  picric  acid,  and  beyond 
that  its  power  and  properties  remain  to  be  developed. 

Bellite  is  a  Swedish  explosive  which  was  discovered  by 
Carl  Lamm,  of  the  Rotebro  Explosive  Manufactory,  Limited, 
near  Stockholm,  and  consists  of  a  mixture  of  ammonium 


1 86  LECTURES   ON  EXPLOSIVES. 

nitrate  and  meta-di-nitrobenzene  in  the  following  propor- 
tions: 

Ammonium  nitrate 5  parts 

Meta-di-nitrobenzene I      " 

These  ingredients  are  heated  up  to  80°  or  90°  C.  (the 
melting-point),  and,  when  in  a  melted  condition,  are  mixed 
with  saltpetre,  forming  a  true  explosive  compound.  When 
pressed  warm  and  granulated  it  has  a  specific  gravity  of  from 
1.2  to  1.4,  and  a  gravimetric  density  of  from  .800  to  .875. 

Heated  in  an  open  vessel  bellite  loses  its  consistency  at 
90°  C.,  but  does  not  begin  to  separate  below  200°  C. ;  at  that 
point  evaporation  begins,  and  increases  with  a  higher  tempera- 
ture, without  explosion,  however.  Suddenly  heated  bellite 
burns  with  a  sooty  flame,  but  upon  the  removal  of  the  source 
of  heat  it  ceases  to  burn  and  assumes  a  caramel-like  structure, 
the  ingredients  being  the  same  as  in  its  original  state  with  the 
exception  of  a  smaller  proportion  of  saltpetre.  After  it  has 
been  pressed  bellite  is  not  especially  hygroscopic;  if  pressed 
while  hot,  the  subsequent  increase  of  weight  does  not  exceed 
2  per  cent. 

During  February  1889  an  experimental  exhibition  of  the 
properties  of  bellite  was  given  at  Chadwell  Heath,  England, 
and  the  following  tests  were  made  in  the  presence  of  a  large 
number  of  visitors: 

1.  A  charge  of  i£  pounds  of  the  explosive  was  placed  in 
a  can  and  fired  under  water.      The  can  being  water-tight,  this 
experiment  might  have  been  omitted. 

2.  A  4-ounce  charge  of  bellite — which  somewhat  resem- 
bled  a   stick  of   sulphur — was   broken  in  two,   and  one  end 
thrown  into  a  coal  fire,  where  it  melted  and  burned  quietly. 
The  other  end  of  the  stick  was  placed  upon  a  -f -inch  iron  plate 
and    exploded    by   means    of    a    detonator.      The    plate  was 
bulged.      This    experiment    illustrated    the    fact    that    while 
bellite  cannot  be  exploded  by  ordinary  combustion,  yet  when 
detonated  by  proper  means  it  exerts  a  powerful  force. 

3.  A  mass  of  iron  weighing  120  pounds  was  dropped  from 


CLA  SSI  PICA  TION  OF  EXPL  OSI VE   COMPO  UND  S.         187 

a  height  of  about  16  feet  upon  5  charges  of  bellite  placed 
on  an  iron  plate.  The  explosive  was  ground  to  pieces  with- 
out explosion. 

4.  Five  ounces  of  this  crushed  bellite  were  placed  in  a  can 
and  detonated  in  contact  with  a  steel-faced  iron  rail,  the  rail 
being  fractured  by  the  force  of  the  explosion. 

5.  A    quantity    of    bellite  was    mixed  with    I    pound   of 
blasting-powder    and    buried    in    a  hole   3   feet  deep.      This 
charge    was  fired   by  a    plain   powder  fuse,    but  the   bellite, 
although  blackened  and  burned  somewhat  on  its  surface,  was 
thrown  about  unexploded. 

6.  A  charge  of  bellite  was  fired  like  a  bullet  from  a  small 
arm  against  a  f-inch  iron  plate.      Pieces  of  the  explosive  were 
found  adhering  to  the  plate  unexploded. 

7.  The  ballistic  properties  of  bellite  were  illustrated  by 
firing  from  a  mortar  a  32-pound  shot,  first  with  a  charge  of 
\  pound  of  powder,  and  then  with  J  pound  of  bellite.      In 
the  first  case  the  range  attained  was  40^  yards;   in  the  latter 
95  yards. 

8.  Its  explosive  effect  was  next  compared  with  that  of 
dynamite    under    similar  conditions.      Four   ounces   of  each 
explosive  were  placed   upon  -f-inch  iron  plates,  covered  with 
moist  clay,  and  detonated.     The  effects  were  about  the  same, 
although  it  was  claimed  that  the  explosive  effect  of  bellite  was 
more  widely  distributed  than  that  of  dynamite. 

9.  It  was  next  tried  to  explode  bellite  in  mines  by  means 
of  ordinary  powder  fuses.      In  all  cases  the   bellite   failed  to 
explode,  while  gunpowder  was  readily  exploded  under  similar 
circumstances. 

10.  A  charge  of  8  pounds  of  bellite  was  placed  in  a  mine 
3  feet  deep  beneath  a  length  of  railway  line  laid  in  chairs  fixed 
in  cross-sleepers  with  fishes,  etc.,  complete,  and  exploded  by^ 
means  of  a  detonating  fuse.      The  entire  structure  for  many 
feet  was  thrown  in  the  air,  the  rails  being  broken  in  one  place 
and  bent  in  others,  fishes  broken,  etc. ;  while  the  sleepers  were 
torn  and  split,  one  chair  broken,  and  a  crater  about    12   feet 
in  diameter  opened. 


1 88  LECTURES   ON  EXPLOSIVES. 

Some  of  its  other  properties,  such  as  its  freedom  from 
flame,  the  harmless  nature  claimed  for  its  products  of  com- 
bustion, etc.,  were  not  tested. 

In  connection  with  these  experiments  the  claims  of  the 
inventor  are  given.  M.  Lamm  claims  for  bellite  the  following 
advantages : 

1.  That  it  is  one  of  the  most  powerful  explosives  known, 
being  stronger  than  guncotton,  gunpowder,  or  dynamite. 

2.  That  it  possesses  qualities  of  safety  entirely  foreign  to 
explosive    substances   generally,  as  follows:    It    presents    no 
danger   whatever    in    manufacture;     it    cannot    be    made    to 
explode  by  friction,  shock,  or  pressure;   it  cannot  be  made  to 
explode  by  fire,  lightning,  or  electricity;  it  can  only  be  made 
to  explode  by  means  of  a  detonating  cap,  and  is  therefore 
absolutely  safe. 

3.  That    upon    being    exploded     no    noxious    gases    are 
given,  off,  and  therefore  it  is  particularly  adapted  to  blasting 
in  mines,  etc. 

4.  That  bellite,  made  expressly  for  coal  or  rock  blasting, 
does  not  shatter  like  dynamite,  but  detaches  the  material  in 
large  blocks  with  but  a  small  percentage  of  dust. 

5.  That  it  does  not  undergo  any  chemical  change  from 
time   nor  atmospheric   influences,  always  retaining  its   non- 
explosive  character  until  the  fulminating  cap  is  applied  to  it. 

6.  That  it  can  be  used  in  shells  that  would  prove  of  a 
terribly   destructive  character,   and   that  such  shells  may  be 
fired   from  guns  of   large  calibre  with   the  service  charge  of 
powder  without  risk  to  the  piece. 

/.  That  bellite  can  be  safely  manufactured  in  tropical 
climates,  and  transported  by  land  or  sea  as  ordinary  merchan- 
dise. 

8.  That  it  requires  no  thawing,  as  it  does  not  freeze  or 
change  its  character  in  even  the  coldest  weather. 

9.  Finally,  that  it  can  be  profitably  manufactured  and  sold 
at  a  lower  price  than  dynamite  or  any  other  explosive  pos- 
sessing equal  force. 

Securite. — This  explosive  is  almost  identical  with  bellite, 


CLA  SSIFICA  TION  OF  EX  PL  OSI VE   COMPO  UND  S.         1^9 

differing  only  in  the  proportions  of  the  ingredients  when  first 
introduced.  Originally  securite  consisted  of  74  per  cent  of 
ammonium  nitrate  and  26  per  cent  of  meta-di-nitrobenzene. 
Recently,  however,  new  varieties  of  this  explosive  have  been 
introduced,  which  contain  tri-nitro-benzene,  and  di-  and  tri- 
nitrobenzene;  also  a  variety  known  as  Flameless  Securite, 
made  by  adding  ammonium  oxalate  to  the  varieties  men- 
tioned. Securite  is  a  bright-yellow  granular  substance  which 
is  said  to  be  non-hygroscopic,  and  capable  of  being  kept  for 
any  length  of  time  without  undergoing  any  change.  It  is 
insensitive  to  friction  and  percussion,  cannot  be  exploded  by 
a  flame  or  incandescent  body,  requiring  a  detonating  cap  to 
provoke  an  explosion.  Its  strength  is  said  to  be  equal  to  that 
of  dynamite  No.  I. 

Nitro-toluene. — Similar  nitro-compounds  may  be  derived 
from  toluene  as  have  been  enumerated  under  benzene,  but 
only  one  such  derivative,  namely,  di-nitro-toluene,  has  as  yet 
been  found  of  practical  value  in  its  application  to  explosives. 
In  preparing  di-nitro-toluene  it  has  been  found  most  advan- 
tageous to  use  the  strongest  acids  (nitric  and  sulphuric)  and 
to  treat  toluene  directly,  rather  than  prepare  the  mono- 
compound  and  renitrate  that  product.  As  in  the  case  of 
benzene  three  isomeric  compounds  are  produced.  Dinitro- 
toluene  is  a  solid  crystalline  body,  the  crystals  having  the 
form  of  slender  needles;  it  melts  at  about  71°  C.  is  soluble  in 
boiling  water  and  alcohol,  and  decomposes  at  temperatures 
above  300°  C.  It  is  not  itself  explosive,  but  lends  itself  readily 
to  the  formation  of  various  grades  of  explosives  when  mixed 
with  other  explosive  substances.  It  has  recently  attracted 
attention  on  account  of  its  use  in  the  manufacture  of  smoke- 
less powders. 

Mono-nitronaphthalene. — Like  benzene,  naphthalene, 
when  treated  with  nitric  acid,  gives  rise  to  a  large  class  of 
nitro-compounds,  many  of  which  have  been  experimented 
with  in  making  explosives.  The  formula  for  naphthalene  is 
C10Hb,  and  the  molecular  arrangement  of  the  atoms  may  be 
represented  graphically  as  follows  : 


IQO  LECTURES  ON  EXPLOSIVES. 

H         H 

I  I 

H\  /C\/C\  /H 

xc      c      c' 

I      II      I 

c       c      c 

H/  \.^/\^S  ^H 


I      I 

H        H 

As  in  the  case  of  benzene,  this  formula  serves  to  explain 
the  great  number  of  isomeric  substitution-products. 

Mono-nitronaphthalene  may  be  made  by  introducing 
finely  pulverized  naphthalene  into  a  mixture  consisting  of 
four  parts  of  nitric  acid  (sp.  gr.  1.400)  and  five  parts  of 
sulphuric  acid  (sp.  gr.  1.840),  taking  care  that  the  tempera- 
ture does  not  fall  below  160°  F.  so  as  to  prevent  solidification 
of  the  nitro-compound  during  the  process  of  conversion. 
When  the  reaction  is  complete,  the  entire  contents  of  the 
flask  (or  other  vessel)  are  decanted  and  allowed  to  cool,  and 
the  nitronaphthalene  solidifies.  The  solid  mass  is  then 
removed,  melted  with  hot  water,  and  thoroughly  washed  with 
constant  agitation  until  free  from  all  traces  of  acidity.  A 
better  method  of  preparing  this  substance  is  to  dissolve  the 
naphthalene  in  glacial  acetic  acid  and  add  to  the  solution 
nitric  acid  (sp.  gr.  1.420),  in  the  proportion  of  four  parts  of 
HNO3  to  every  one  part  of  naphthalene  dissolved.  As  soon 
as  all  of  the  nitric  acid  has  been  added  the  entire  contents  of 
the  vessel  are  brought  to  gentle  ebullition,  and  this  tempera- 
ture maintained  for  fifteen  minutes.  Upon  cooling  the 
mono-nitro-naphthalene  is  deposited  in  long,  slender,  yellow 
prismatic  needles.  It  melts  at  about  6k°  C.,  is  only  slightly 
volatile  when  heated,  is  insoluble  in  water,  but  readily  dis- 
solves in  alcohol,  benzene,  carbon  bisulphide,  and  is  decom- 
posed when  heated  above  300°  C. 

Although  not  itself  explosive,  mixed  with  other  substances 
it  is  used  in  the  manufacture  of  a  large  class  of  explosives. 

Di-,  Tri-,  and  Tetra-nitronaphthalene. — The  di-deriva- 
tive  of  naphthalene  may  be  made  by  dissolving  naphthalene 


CLASSIFICATION  OF  EXPLOSIVE    COMPOUNDS.         IQI 

in  boiling  nitric  acid  (sp.  gr.  1.500),  or  by  treating  mono- 
nitronaphthalene  with  nitric  acid  (sp.  gr.  1.52)  in  the  cold,  or 
by  treating  naphthalene  at  a  temperature  of  about  70°  C.  with 
a  mixture  of  one  part  of  concentrated  nitric  acid  and  two 
parts  of  sulphuric  acid. 

By  boiling  di-nitronaphthalene  with  fuming  nitric  acid 
tri-nitronaphthalene  is  formed,  and  by  subjecting  the  same 
derivative  to  the  prolonged  action  of  boiling  nitric  acid 
(fuming)  it  is  converted  into  tetra-nitronaphthalene.  These 
various  nitronaphthalenes  are  separated  from  the  acids  and 
purified  as  described  in  the  preparation  of  the  mono-nitro 
derivative. 

Di-nitronaphthalene  forms  brilliant  yellowish  crystals, 
which  when  heated  gradually  melt  at  about  185°  C.,  but  if 
subjected  suddenly  to  high  temperatures  deflagrate.  It  is 
sparingly  soluble  in  alcohol,  ether,  carbon  bisulphide,  and 
cold  nitric  acid,  but  dissolves  readily  in  benzene,  acetic  acid, 
and  turpentine. 

Tri-nitronaphthalene  crystallizes  out  in  yellowish  tabular 
crystals,  and  the  tetra-nitro-compound  in  prisms  of  the  same 
color,  both  of  which  explode  when  heated.  All  of  the  nitro- 
naphthalenes have  been  experimented  with  in  connection  with 
explosives,  and  combined  with  other  substances  form  powders 
which  have  been  patented  in  Belgium  under  the  name  of 
Favier  Powders.  These  powders  are  also  known  in  England 
as  Ammonites,  and  in  other  countries  as  Nitramites. 

Volney's  Powders. — In  view  of  the  attention  which 
nitro-substitution  compounds  are  receiving  at  present,  it  may 
be  of  interest  to  note  the  letters  patent  granted  Mr.  C.  W. 
Volney  in  1874. 

His  invention  consists  in  mixing  nitrated  naphthalene  with 
an  oxidizing  agent.  By  acting  upon  naphthalene  with  nitric 
acid  of  varying  strength,  substances  are  produced  of  corre- 
sponding degrees  of  nitration.  Thus  with  nitric  acid  having 
the  specific  gravity  of  1.40  the  mono-nitronaphthalene  is 
produced : 

C,0HS  +  HNO,  =  C,.H,(NO,)  +  H,O. 


I92  LECTURES   ON  EXPLOSIVES. 

While  by  using  a  mixture  of  strong  sulphuric  acid  (sp.  gr. 
1.845)  and  nitric  acid  having  a  specific  gravity  of  1.50  we 
obtain  the  tetra-nitronaphthalene: 

C10H8  +  8H3S04  +  4HN03  =  C]0H4(NO2)4  +  8H2SO4  +  4H,O. 

All  of  the  nitronaphthalenes  will  form  explosive  com- 
pounds when  mixed  with  oxidizing  agents  which  can  supply 
sufficient  oxygen  to  oxidize  the  surplus  carbon ;  and  it  is 
evident  that  the  higher  the  degree  of  nitration  of  the  naph- 
thalene, the  less  of  the  oxidizing  agent  will  be  required,  while 
at  the  same  time  the  greater  will  be  the  breaking  power  of 
the  explosive. 

Thus  in  order  to  make  an  explosive  of  moderate  breaking 
power,  which  is  therefore  better  adapted  to  military  purposes, 
or  blasting  in  soft  and  fissured  rock,  etc.,  the  mono-nitro- 
naphthalene  is  used,  being  prepared  commercially  by  incor- 
porating 

Naphthalene 100  pounds 

Nitric  acid  (sp.  gr.  1.40) 400       " 

and  leaving  these  substances  in  contact  for  four  or  five  days, 
at  the  end  of  which  time  the  naphthalene  has  been  converted 
into  a  brown  crystalline  mass,  which  is  thoroughly  washed 
with  water,  dried  and  pulverized.  This  the  inventor  calls 
"  Nitrated  Naphthalene  No.  II." 

The  explosive  made  from  this  product  is  formed  by  mix- 
ing thoroughly 

Nitrated  naphthalene  No.  II 1. 06  pound 

Saltpetre 3.30      " 

Sulphur 0.51       " 

These  substances  can  be  pulverized  and  mixed  in  the 
same  manner  as  in  the  manufacture  of  ordinary  gunpowder. 

To  prepare  an  explosive  of  great  breaking  power,  such  as 
would  be  adapted  to  filling  torpedoes,  submarine  blasting, 
blasting  of  hard  rock,  etc.,  the  tetra-nitronaphthalene  is  used, 


CLASSIFICATION  OF  EXPLOSIVE   COMPOUNDS.         IQ3 

which,  prepared  as  follows,  is  called  "  Nitrated  Naphthalene 
No.  I."  Commercially  this  nitro-compound  is  made  by 
treating  naphthalene  with  a  mixture  of  two  parts  of  strong 
nitrosulphuric  acid  (sp.  gr.  1.845)  an^  one  part  of  nitric  acid 
(sp.  gr.  1.50)  at  a  temperature  of  100°  C.,  in  the  proportion  of 

Napthalene 100  pounds 

Nitrosulphuric    acid    400        *  * 

At  the  end  of  one  hour  the  reaction  is  finished,  all  of  the 
naphthalene  having  been  converted  into  a  bright  yellow  crys- 
talline mass,  which  is  washed,  dried,  and  pulverized  as  already 
indicated. 

A  very  powerful  explosive  is  made  from  this  nitro-substi- 
tution  product,  as  follows : 

Nitrated  Naphthalene  No.  !„ 2.18  pounds 

Saltpetre, 0.19       " 

Sulphur o.  16        " 

In  both  of  these  powders  any  other  nitrate  or  any  chlorate 
may  be  substituted  for  saltpetre. 

These  powders  are  of  a  yellow  color,  and  are  unusually 
insensitive  to  friction,  percussion,  concussion,  and  heat,  and  are 
therefore  safely  handled,  stored,  and  transported.  When  un- 
confined  except  in  the  form  of  cartridges,  they  ignite  and  burn 
away  harmlessly.  It  requires  a  powerful  detonator,  or  a 
priming  of  guncotton,  nitroglycerine,  or  dynamite,  to  develop 
their  full  power.  Experiments  in  the  Artillery  School  labo- 
ratory show  the  relative  strength  of  powders  Nos.  I  and  II  to 
be  respectively  58.44  and  53.18,  as  compared  with  standard 
nitroglycerine. 

Favier  Explosives. — In  his  investigations  looking  to  a 
reduction  of  the  inherent  dangers  of  nitroglycerine,  M.  Favier 
concluded  that  it  was  possible  to  make  an  explosive  in  which 
the  nitrogen  and  carbon  elements  were  simply  placed  in  juxta- 
position, but  not  combined.  Acting  upon  this  conclusion  he 
patented  certain  mixtures,  which  are  known  in  Belgium  as 
Favier  Powders,  but  in  England  they  are  called  Ammonites, 
and  in  other  countries  Nitramites. 


194  LECTURES   ON  EXPLOSIVES. 

According  to  his  patents,  M.  Favier  seeks  "to  replace 
explosive  nitrogen  compounds,  like  fulmicotton  and  nitro- 
glycerine, in  which  the  nitrogen  compound  and  hydrocarbon 
elements  are  united  in  one  definite  compound,  by  simple 
mixtures  of  these  same  elements."  He  further  proposes  to 
use  in  the  fabrication  of  his  new  powders  substances  which 
under  ordinary  conditions  are  absolutely  stable,  but  which 
by  greatly  increasing  the  initial  detonation,  either  by  increas- 
ing the  charge  of  fulminate  in  ordinary  blasting-caps,  or  by 
using  an  initial  priming  of  guncotton  or  dynamite,  could  be 
fully  detonated.  These  principles  were  applied  in  Belgium 
in  1887  to  a  mixture  having  the  following  composition: 

Ammonium  nitrate 75  parts 

Resin 5      " 

Charcoal 20     " 

The  mixture  was  forcibly  compressed  into  a  hollow  cylin- 
der, and  the  interior  of  this  cylinder  was  filled  with  dynamite, 
which  formed  the  initial  detonator.  It  was  found  that,  while 
a  fulminate  cap  alone  would  not  explode  the  compressed 
mixture,  if  the  mixture  were  granulated  it  could  be  detonated 
by  2  grammes  of  fulminate. 

In  his  more  recent  powders  M.  Favier  has  materially 
changed  the  compositions.  The  enveloping  cartridge  is 
made  of  ammonium  nitrate  and  nitronaphthalene  "in  the 
proportions  necessary  to  produce  a  gas  at  the  moment  of  oxi- 
dation." These  proportions  are  appproximately  as  follows: 

Ammonium  nitrate . . .  = 90  parts 

Nitronaphthalene 10      " 

The  nitronaphthalene  is  melted  and  poured  around  the 
ammonium  nitrate,  which  is  thus  enclosed  for  protection  on 
account  of  its  hygroscopic  properties.  Briefly  described,  the 
process  of  manufacture  is  as  follows: 

The  nitrate  is  thoroughly  dried  by  passing  it  slowly  upon 
an  Archimedean  screw  through  a  trough  warmed  by  steam, 
and  is  then  pressed  into  a  warmed  former  and  sprinkled  with 


CLASSIFICATION  OF  EXPLOSIVE   COMPOUNDS.         1 95 

melted  nitronaphthalene.  In  this  manner  a  homogeneous 
roll  is  formed  which  passes  next  to  the  graining-machine. 
When  granulated  the  grains  are  sifted,  the  smaller  particles 
being  reserved  for  intermediary  detonators  to  be  placed  in 
the  cartridge-core,  while  the  larger  grains  are  moulded  warm 
into  hollow  cartridges,  which  are  subsequently  covered  with 
paraffin,  and  after  the  detonator  is  inserted  the  whole  is 
enveloped  in  paraffin  paper. 

In  France  the  government  has  secured  control  of  these 
powders,  and  in  the  factory  at  Saint-Denis  five  varieties  are 
made: 

I.   Grisounite — Ammonium  nitrate 95.5  parts 

Tri-nitronaphthalene 4. 5      ' ' 

II.    Grisounite — Ammonium  nitrate 92.0     " 

Di-nitronapthalene 8.0     " 

III.  Poudre  Favier,  No.  i — Ammonium  nitrate. .  87.5      " 

Di-nitronaphthalene.    12.5      " 

IV.  "  "       No.  2 — Ammonium  nitrate. .   44.0     " 

Sodium  nitrate 40.0  " 

Di-nitronaphthalene.  16.0  " 

V.          "           "       No.  3 — Sodium  nitrate 75.0  " 

Mono-nitronaphtha- 

lene 25.0  " 

The  ingredients  used  in  these  powders  being  very  stable 
substances,  they  can  be  manipulated  with  great  security,  and 
their  transport  presents  no  danger.  It  is  claimed  for  them 
that  they  are  insensible  to  shock,  fire,  and  cold ;  in  fact  their 
excess  of  stability  is  their  only  fault,  as  it  requires  one 
gramme  of  the  fulminate  of  mercury  to  provoke  detonation. 
On  the  other  hand,  the  hygroscopic  nature  of  ammonium  ni- 
trate, which  forms  so  large  a  proportion  of  these  powders, 
requires  great  precaution  in  storage. 

Of  the  varieties  given  above,  Poudre  No.  3  seems  to  give 
the  best  results. 

Emmensite. — In  January  1888  letters  patent  were  granted 
to  Dr.  Stephen  H.  Emmens,  of  New  York,  for  a  new  organic 


196  LECTURES   ON  EXPLOSIVES. 

acid  discovered  by  him,  to  which  the  name  of  Emmens  Acid 
has  been  given,  and  the  compounds  formed  with  this  acid  bear 
the  general  name  of  Emmensite. 

According  to  Dr.  Emmens,  the  discovery  of  the  so-called 
Emmens  Acid,  or  EACID,  was  purely  accidental,  and  resulted 
from  a  mixture  of  picric  and  nitric  acids,  the  latter  of  <4  ex- 
ceptionally high  specific  gravity,"  which  had  been  gently 
warmed  and  set  aside  for  some  weeks,  at  the  end  of  which 
period  the  new  acid  had  crystallized  out.  The  existence  of 
the  new  acid  has  been  questioned,  and  Emmens  Acid,  or  Eacid, 
has  been  considered  by  several  eminent  chemists  merely  an 
isomeric  form  of  picric  acid.  According  to  an  analysis  by  Dr. 
Wurtz,  the  relative  percentage  compositions  of  eacid  and  picric 
acid  are  as  follows: 

Eacid.  Picric  Acid. 

Carbon 31.84  31-44 

Hydrogen 2.04  1.31 

Nitrogen 17.14  iS-34 

Oxygen 48.98  49.91 


100.00         100.00 

Dr. Wurtz  assigned  to  this  acid  the  formula 
H,C.C,,H.(NO,).0.-OH. 

and  regarded  it  as  intermediate  between  tri-nitro-phenol  and 
tri-nitrocrosol.  Professor  Remscn,  of  the  Johns  Hopkins 
University,  declared  the  new  acid  to  be  merely  a  very  pure 
form  of  picric  acid,  while  Lieut.  John  P.  Wisser,  of  the 
First  U.  S.  Artillery,  assistant  professor  of  chemistry  at  the 
U.  S.  Military  Academy,  after  carefully  examining  the  new 
acid,  stated  that  it  was  "  simply  picric  acid  which  has  mechan- 
ically absorbed,  probably  in  crystallizing,  the  fumes  of  nitric 
acid  or  the  acid  itself."  On  the  other  hand,  the  inventor,  Dr. 
Emmens,  and  Dr.  Wurtz,  of  Pittsburgh,  have  maintained  that 
the  newly  discovered  acid  is  not  identical  vi\\h.  pure  picric  acid. 
Emmens  acid  has  been  obtained  in  the  Artillery  School  lab- 
oratory by  dissolving  picric  acid  at  a  gentle  heat  in  fuming 


CLASSIFICATION  OF  EXPLOSIVE   COMPOUNDS.         1 97 

nitric  acid  (sp.  gr.  1.500  to  1.550)  and  evaporating  the  solu- 
tion to  about  two  thirds  of  the  original  volume.  Upon  cool- 
ing, the  new  acid  crystalizes  out 'in  lc:ig,  transparent  crystals, 
varying  in  form  from  prismatic  to  rhomboidal.  In  color  it 
also  differs  from  picric  acid,  possessing  a  greenish-yellow  rather 
than  straw  yellow  color;  it  is  also  less  soluble  in  water  and 
alcohol,  and  melts  at  a  lower  temperature,  evolving  brownish- 
red  fumes  and  undergoing  change  of  color.  All  of  these 
points  of  difference,  however,  may  be  explained  by  the  theory 
of  Lieut.  Wisser  as  to  the  composition  of  the  new  acid. 

In  the  specifications  of  the  letters  patent  granted  on  March 
4,  1890,  Dr.  Emmens  describes  the  methods  of  preparing 
emmensite  substantially  as  follows: 

"  The  materials  I  employ  are  such  hydrocarbon  substitu- 
tion-derivatives as  are  capable  of  fusion  by  heat  without 
decomposition,  and  are  also  capable,  when  fused,  of  dissolving 
the  nitrates  of  soda,  potash,  ammonia,  which  are  the  preferred 
oxidants.  The  most  suitable  hydrocarbons  for  the  purpose, 
so  far  as  I  have  discovered,  are  the  tri-nitrophenols,  tri-nitro- 
cresols,  and  (if  the  working  temperatures  do  not  exceed 
120°  C.)  the  new  acid  patented  to  me  January  10,  1888. 

*  The  conditions  under  which  the  new  type  of  explosives 
is  produced  consist  in  the  employment  of  a  sufficient  degree 
of  heat  and  in  continuing  this  heat  until  actual  liquefaction  of 
the  mixture  is  attained.  The  manner  in  which  I  carry  out 
my  new  process  of  manufacturing  explosives  is  as  follows:  I 
take  two  open  vessels,  both  heated,  by  steam-jackets  or  by 
any  other  convenient  method,  to  the  same  temperature.  In 
one  of  these  I  place  the  tri-nitrophenol,  and  in  the  other  I 
place  the  nitrate  of  soda  or  other  oxidant  in  a  finely  pulver- 
ized and  dried  condition.  When  the  combustible  is  entirely 
fused  I  add  thereto  the  heated  oxidant  in  small  quantities  at 
a  time,  and  I  stir  the  mixture  thoroughly.  I  then  gently 
raise  the  heat  until  the  oxidant  becomes  fully  liquefied,  or  so 
combined  with  the  combustible  as  to  form  a  semi-fluid  homo- 
geneous mass.  The  mixture  is  then  removed  from  the  vessel 
and  allowed  to  cool  for  use." 

By  varying  the  proportions  of  the  several  ingredients,  as 


198  LECTURES   ON  EXPLOSIVES. 

well  as  the  ingredients  themselves,  an  infinite  number  of 
explosives  may  be  obtained,  all  of  which  would  belong  to  the 
class  of  emmensites. 

Practically  the  inventor  recommends  three  grades,  as 
follows : 

No.  35,  to  be  used  for  blasting  purposes,  consisting  of 
picric  acid  and  sodium  and  ammonium  nitrates;  No.  259,  for 
military  and  naval  use,  shell  and  torpedo  charges,  etc.,  con- 
sisting of  picric  acid,  di-nitrobenzene,  and  sodium  and 
ammonium  nitrates;  and  No.  5,  as  a  substitute  for  gunpow- 
der, consisting  of  picric  acid,  sodium  nitrate,  and  charcoal  or 
flour. 

These  grades  have  been  made  upon  a  small  scale  in  the 
Artillery  School  laboratory  and  subjected  to  various  tests  as 
to  strength,  stability,  etc.  As  the  result  of  the  earlier 
experiments  (made  over  five  years  ago),  the  claims  for  stability 
and  great  explosive  force  made  for  this  explosive  were  not 
verified,  and  with  the  conviction  that  the  investigation  had 
been  most  impartially  and  carefully  conducted,  those  results 
were  incorporated  in  the  former  edition  of  these  lectures,  as 
well  as  in  the  pamphlet  prepared  for  the  instruction  of  artillery 
gunners.  Subsequent  experiments  by  myself,  and  particularly 
investigations  by  the  Naval  Bureau  of  Ordnance,  as  well  as 
by  the  Board  of  Ordnance  and  Fortifications  of  the  Army, 
have  convinced  me  that  it  is  possible  to  make  emmensite 
which,  when  loaded  in  shells,  torpedoes,  or  other  receptacles 
that  may  be  closed  tightly  so  as  to  protect  it  from  atmos- 
pheric changes  (and  especially  exclude  moisture),  will  preserve 
its  stability  and  explosive  force  for  years.  Exposed  to  damp 
air,  however,  emmensite  quickly  absorbs  moisture  and  develops 
acidity.  Such  samples  as  have  been  experimented  with 
have  either  been  carefully  prepared  from  chemically  pure 
materials,  or  have  been  procured  from  commercial  sources, 
although  I  would  have  preferred  to  experiment  with  samples 
direct  from  the  factory,  and  endeavored  to  secure  such  sam- 
ples several  times.  As  the  result  of  the  investigations 
referred  to  (by  the  military  and  naval  authorities),  it  has  been 


CLASSIFICATION   OF  EXPLOSIVE    COMPOUNDS.         199 

shown  that  emmensite  when  freshly  made,  or  when  protected 
from  dampness,  possesses  great  explosive  force,  and  moreover 
may  be  safely  fired  as  shell  charges  from  high-powered  rifled 
ordnance,  although  it  would  seem  from  these  experiments  that 
there  is  a  limit  to  the  amount  that  can  be  thus  fired. 

The  importance  of  this  last  property  overshadows  all  other 
claims  yet  made  for  this  explosive,  especially  since  it  has  also 
been  demonstrated  that  shells  charged  with  emmensite  do  not 
require  special  fuses,  but  that  an  explosion  of  a  high  order 
may  be  developed  by  means  of  a  simple  fuse  which  may  be 
ignited  by  an  ordinary  percussion-cap. 

Gelbite. — Gelbite  is  but  another  form  of  emmensite,  and 
was  patented  by  the  inventor  of  that  explosive.  According 
to  letters  patent,  it  is  "  an  explosive  substance,  consisting  of 
paper,  or  paper-stock,  converted  into  a  nitro-compound  and 
impregnated  with  ammonia  and  picric  acid." 

It  may  be  prepared  as  follows:  Sheets  of  paper,  of  con- 
venient size,  are  immersed  in  a  mixture  of  nitric  and  sulphuric 
acids  (in  proportions  of  I  to  3)  for  about  three  minutes,  and 
are  then  removed  and  washed,  first  with  water,  and  then 
with  a  solution  of  ammonium  carbonate.  It  is  then  steeped 
in  a  hot  solution  of  picric  acid  and  allowed  to  remain  until 
thoroughly  saturated,  the  result  being  a  sheet  of  nitrocellu- 
lose impregnated  with  picric  acid,  ammonium  picrate,  nitrate, 
and  sulphate,  the  proportions  of  which  vary  according  to  the 
treatment.  Thus  prepared  gelbite  has  the  appearance  of  a 
sheet  of  yellow  paper.  Ignited  it  burns  quickly,  with  but 
little  smoke;  the  fumes,  however,  possess  all  the  disagreeable 
features  of  picric  acid.  It  has  been  proposed  to  use  gelbite 
as  a  propellant  in  small  arms,  but  experiments  in  that  direc- 
tion have  not  justified  its  adoption. 

Roburite. — This  explosive  was  invented  by  Dr.  Carl  Roth, 
a  German  chemist,  and,  according  to  the  license  authorizing 
its  manufacture  in  Great  Britain,  it  consists  of 

"  (a)  Nitrate  of  ammonium  with  or  without  an  admixture 
of  nitrate  of  sodium  and  neutral  sulphate  of  ammonium,  or 
either  of  them,  provided  that  the  amount  of  nitrate  of  sodium 


200  LECTURES   ON  EXPLOSIVES. 

shall  in  no  case  exceed  50  per  cent  of  the  total  amount  of 
nitrates  present,  and 

"  (b)  Thoroughly  purified  chlorinated  di-nitrobenzole 
with  or  without  the  addition  of  thoroughly  purified  chloro- 
nitronaphthalene  and  chloro-nitrobenzole;  provided  (i)  that 
such  chlorinated  di-nitrobenzole  shall  not  contain  more  than 
four  (4)  parts  by  weight  of  chlorine  to  every  one  hundred 
(100)  parts  by  weight  of  chlorinated  di-nitrobenzole;  and  (2) 
that  the  proportions  of  chloro-nitronaphthalene  and  chloro- 
nitrobenzole  shall  not  amount  to  more  than  2  per  cent  and  5 
per  cent  respectively  of  the  finished  explosive." 

In  addition  to  these  ingredients  nitronaphthalene  is  also 
sometimes  used.  In  introducing  chlorine  into  the  nitro- 
compound,  Dr.  Roth  claims  to  have  greatly  increased  the 
dynamic  effect  of  the  explosive,  the  formula  for  chloro-di- 
nitrobenzole  being  C8H3Cl(NOa)2,  and  the  percentages  of 
nitrogen  and  chlorine  being  therefore  respectively  13.82  and 
17.53.  Roburite  is  made  by  first  thoroughly  drying  and  pulver- 
izing the  ammonium  nitrate,  which  is  then  heated  in  a  closed 
steam-jacketed  vessel  to  80°  C.  The  chloro-di-nitrobenzole 
is  melted  and  added  to  the  heated  ammonium  salt  and  the 
ingredients  thoroughly  incorporated  by  constant  stirring. 

Thus  made,  roburite  is  a  yellowish-brown  powder,  possess- 
ing the  characteristic  odor  of  nitrobenzole  (bitter  almonds) 
and  having  a  specific  gravity  of  1.40.  It  burns  quickly,  but 
cannot  be  exploded  by  concussion,  pressure,  friction,  shock, 
or  fire. 

It  does  not  freeze,  and  when  burned  or  exploded  it  does 
not  evolve  deleterious  fumes.  Among  other  advantages 
claimed  for  roburite  are  that  it  is  practically  flameless,  so  that 
it  can  be  safely  used  in  fiery  mines;  that  its  action  is  rending, 
and  not  pulverizing,  which  makes  it  particularly  well  adapted 
to  quarrying  and  coal-mining;  that  it  can  be  detonated  at  a 
very  low  temperature;  and  finally  that  it  can  be  exploded 
only  by  using  a  very  powerful  detonator  (one  containing  at 
least  one  gramme  of  mercury  fulminate). 

On  the  other  hand,  however,  on  account  of  the  extremely 


CLASSIFICATION  OF  EXPLOSIVE   COMPOUNDS.         2OI 

deliquescent  nature  of  ammonium  nitrate,  it  is  necessary  to 
protect  the  explosive  from  contact  with  the  air. 

In  1887  this  explosive  was  subjected  to  severe  tests  by 
the  English  Government  under  the  superintendence  of  Major 
Sale,  R.E.,  the  object  of  the  trials  being  to  compare  roburite 
with  guncotton,  dynamite,  and  blasting-gelatine. 

Major  Sale  concluded  his  report  as  follows: 

11  In  summing  up  the  results  of  the  foregoing  experiments 
we  must  bear  in  mind  the  great  difficulty — we  had  almcst 
.said  the  impossibility — of  obtaining  any  absolute  standard  of 
comparison  of  the  relative  strengths  of  two  or  more  explosives. 
Each  will  seem  to  prove  itself  superior  for  certain  purposes. 
Judged,  however,  by  any  standard  of  comparison,  it  appears 
that  the  new  explosive  has  acquitted  itself  very  well,  and, 
especially  when  we  consider  its  absolute  safety,  must  have  a 
great  future  before  it.  Roburite  has  shown  itself  to  be  in 
some  respects  more  powerful  than  dynamite,  to  which  it  is 
likely  to  prove  a  serious  rival  in  the  industrial  field,  although 
the  latter  has  the  proverbial  advantage  of  strong  possession 
of  the  ground.  An  important  element  in  the  struggle  for 
ascendency  will  be  the  price  at  which  roburite  can  be  supplied 
as  compared  with  dynamite,  and  this  will  be,  we  understand, 
strongly  in  favor  of  the  new  substance. 

"  But  although  quite  outside  the  scope  of  Tuesday's 
experiments,  the  great  power  and  safety  of  roburite  seem 
eminently  to  fit  it  for  use  as  a  bursting  charge  for  shells,  into 
which  its  granular  form  would  allow  it  to  be  conveniently 
loaded. 

"  Much  stronger  than  any  picric  powder,  and  doubtless 
better  able  to  withstand  the  concussion  of  the  discharge  of  the 
gun,  an  extended  series  of  trials  would  be  necessary  to  deter- 
mine the  best  mode  of  so  employing  it." 

On  account  of  their  peculiar  properties  bellite,  securite, 
ammonite  (or  Favier  explosives),  and  roburite  are  sometimes 
known  as  "  safety  explosives" 


LECTURE   XI. 


CLASSIFICATION   OF   THE   NITRIC   DERIVATIVE   CLASS   OF 
EXPLOSIVE   COMPOUNDS. 


Nitric  Esters.  Guncotton. — The  second  class  of  explo- 
sive compounds,  nitric  derivatives,  may  be  subdivided  into 
two  classes,  namely,  nitric  ethers  and  nitric  esters,  according 
as  they  are  obtained  by  the  action  of  nitric  acid  upon  simple 
or  complex  alcohols.  The  equations  representing  the  reac- 
tions by  which  explosives  of  this  class  are  formed  are 
analogous  to  those  for  nitro-substitution  compounds,  but 
there  are,  however,  fundamental  reactions  which  characterize 
the  several  nitrated  products. 

As  stated  in  the  preceding  lecture,  there  is  no  reaction 
nor  series  of  reactions  by  means  of  which  the  original  ingre- 
dients which  combine  to  form  the  nitro-substitution  product 
can  be  reproduced.  By  treating  nitric  derivatives,  however, 
with  reducing-agents  the  original  ingredients  may  be  repro- 
duced either  wholly  or  in  part,  according  as  the  derivative  is 
a  nitric  ether  or  a  nitric  ester.  In  the  same  lecture  the 
greater  stability  and  energy  of  nitric  derivatives  as  a  class 
were  mentioned  and  the  thermo-chemical  reasons  therefor 
were  alluded  to,  as  well  as  other  general  characteristic  proper- 
ties which  might  be  accounted  for  by  the  different  arrange- 
ment of  the  atoms  in  the  structure  of  the  explosive  molecules. 
Instead  of  the  nitryl  molecule  or  molecules  (NO2)  being 
attached  directly  to  the  carbon  atoms  in  the  replacement  of 

202 


NITRIC  DERIVATIVE  EXPLOSIVE   COMPOUNDS.       2O3 

such  molecules  for  the  hydrogen  atoms  as  in  the  formation  of 
nitro-substitution  compounds,  in  the  nitric-derivatives  they 
are  connected  through  the  interposition  of  an  atom  of  oxygen. 
We  have  had  occasion  to  refer  to  the  graphic  representation 
of  the  explosive  molecule,  and  to  suggest  the  possible  effect 
of  the  relative  position  of  the  replaced  atoms  upon  its  stabil- 
ity, as  well  as  other  characteristic  properties. 

For  reasons  given  later  on,  the  constitutional  formula  for 
cellulose  has  not  been  definitely  determined,  and  although 
ultimateanalys  is  indicates  its  composition  to  be  C6H]0O6 ,  it  is 
more  probable  that  its  true  composition  is  some  multiple  of 
this  formula,  thus,  «C6H10O6. 

In  order  to  further  illustrate  the  difference  in  the  structure 
of  the  nitro-substitution  and  nitric-derivative  molecule,  and  at 
the  same  time  suggest  a  possible  explanation  of  certain  anom- 
alies connected  with  explosives  of  these  classes,  we  may 
assume  first  that  the  composition  of  cellulose*  is  truly 
represented  by  the  formula  C6H10O6 ,  and  if  we  regard  cellulose 
as  an  alcohol,  as  it  probably  is,  the  formula  may  be  written 
C6H7O2(OH)3 ,  and  graphically  represented  as  follows: 

H      H       H      H       O 

I        I        !        I        II 
H  — C  — C  — C  — C  — C  — C—  H 

II         I         I         I         I 
O       H       O      O       O 

I         I         I 
H       H       H 

By  acting  upon  cellulose  with  nitric  acid,  depending  upon 
the  strength  of  the  acid  and  the  period  of  nitration,  one  or 
more  atoms  of  hydrogen  are  replaced  by  an  equivalent  num- 
ber of  molecules  of  nitryl  with  the  formation  of  mono-,  di-,  or 
tri-nitrocellulose,  but  so  far  no  higher  degree  of  nitration  has 
been  attained  than  the  tri-nitro-derivative.  According  to  the 

*  This  substance  is  taken  for  purpose  of  illustration,  because  its  nitric- 
derivatives  are  the  most  important,  as  well  as  the  best  known,  of  the  class 
of  nitric-esters. 


204  LECTURES   ON  EXPLOSIVES. 

constitutional  formula  for  cellulose,  there  would  seem  to  be  no 
reason  why  the  replacement  should  be  limited  to  three  nitryl 
molecules  for  three  atoms  of  hydrogen.  If,  however,  we 
inspect  the  graphic  formula  assumed  to  represent  the  molec- 
ular structure  of  cellulose,  we  observe  that  three  and  only 
three  atoms  of  hydrogen  are  united  so  as  to  form  hydroxyl, 
and  if  we  assume  further  that  it  is  only  the  hydroxyl  atoms 
of  hydrogen  that  are  replaced  by  nitryl,  and  that  none  others 
are  so  replaceable,  we  have  at  once  a  reason  for  the  limit  to 
the  possible  degree  of  nitration,  and  the  tri-nitro-derivative 
should  be  represented  graphically  as  follows: 

[C6H7Oa(OH)3  +  3HN03  =  C6H702(NO,)3  +  3H,O.] 

H       H      H      H      O 

I         I         I         I         II 
H  — C  — C— C  — C-C  — C— H 

II         I         I         I 
O       H      O       O       O 

I         I         I 

N      N       N 

/A\   l\  /A\ 
oo  oo  oo 

The  mono-  and  di-nitro-derivatives  may  be  similarly  rep- 
resented, in  each  case  the  nitryl  molecule  being  connected 
to  the  carbon  atoms  through  the  interposition  of  the  oxygen- 
atom  of  the  original  hydroxyl.  If,  however,  we  assume  the 
composition  of  cellulose  to  be  represented  by  a  multiple  of 
C6H10O6 ,  as  for  example  by  the  formulae,  C12H20O10 ,  or 
C18HSOOIB,  the  explanation  given  above  is  no  longer  appli- 
cable, as  is  evident  from  an  inspection  of  the  corresponding 
graphic  formulae.  Thus  the  molecule  of  C18H30O16  may  be1 
represented  graphically  as  follows: 


NITRIC  DERIVATIVE  EXPLOSIVE   COMPOUNDS.       2O$ 


This  graphic  formula  shows  that  each  section  of  the  ring 
contains  four  instead  of  three  atoms  of  hydrogen  combined 
in  the  form  of  hydroxyl,  and  it  would  seem,  following  the 
same  line  of  reasoning,  that  there  should  be  at  least  four 
nitro-derivatives  possible ;  but,  as  before  stated,  the  highest 
degree  of  nitration  yet  attained  is  the  tri-nitro-compound,  the 
tetra-nitrocellulose  as  a  more  highly  nitrated  product  being 
unknown. 

Dr.  John  W.  Mallet  offers  in  explanation  of  this  anomaly 
the  following  suggestion,  namely,  that,  instead  of  four  hydro- 
gen atoms  being  combined  in  the  form  of  hydroxyl,  as  repre- 
sented above,  only  three  hydrogen  atoms  are  so  combined, 
the  hydrogen  of  the  fourth  hydroxyl  molecule  being  united 
directly  with  a  carbon  atom,  while  the  corresponding  oxygen 
atom  and  the  only  other  atom  of  oxygen  not  combined  in  the 
form  of  hydroxyl  are  linked  together  with  carbon  atoms  in  the 


206 


LECTURES   ON  EXPLOSIVES. 


quinone  arrangement.     This  arrangement  of  the  atoms  may 
be  represented  as  follows : 


Accepting  the  arrangement  of  the  atoms  in  the  molecule 
as  suggested  by  Dr.  Mallet,  we  again  have  but  three  hydroxyl 
molecules  (in  each  link  of  the  chain),  which,  together  with 
the  hypothesis  that  only  the  hydrogen  atoms  so  combined 
are  replaceable  by  nitryl,  explains  the  limited  degree  to  which 
this  class  of  substances  is  susceptible  of  nitration. 

The  limitation  to  the  degree  of  nitration  is  but  one  of 
a  number  of  anomalies  presented  by  the  various  nitro-sub- 
stitution  products  and  nitric-derivatives,  for  which  the  above 
suggestions  are  offered  as  a  possible  explanation. 

The  importance  of  the  positions  of  the  replaced  atoms 
(already  mentioned)  increases  not  only  with  the  number  of 
such  replacements,  but  also  with  the  nature  of  the  substituted 
atoms  or  radicals.  In  fact  the  relative  positions  may  depend 


NITRIC  DERIVATIVE   EXPLOSIVE    COMPOUNDS.       2O/ 

upon  the  replacing  atoms,  if  dissimilar,  since  in  the  substitu- 
tion they  may  arrange  themselves  according  to  their  electro- 
chemical affinities. 

Finally,  we  may  have  to  invoke  the  aid  of  stereo-chemistry, 
and  apply  the  principles  of  stereo-isomerism  *  in  the  arrange- 
ment of  the  atoms  in  explosive  molecules  before  we  arrive  at 
definite  and  satisfactory  explanations  of  the  capricious  behav- 
ior of  the  majority  of  modern  high  explosives. 

Nitric  Esters. — Logical  sequence,  as  well  as  the  advan- 
tage to  be  gained  by  dealing  with  simpler  compounds  before 
undertaking  more  complex  combinations,  would  seem  to  in- 
dicate that  nitric  ethers  should  be  discussed  before  entering 
upon  the  subject  of  nitric  esters,  but  priority  from  an  histori- 
cal point  of  view  and  important  practical  considerations 
render  it  more  expedient  that  this  order  be  reversed. 

The  principal  explosives  of  this  class  of  nitric-derivatives 
are  obtained  by  acting  upon  some  of  the  various  forms  of 
cellulose  with  nitric  acid. 

These  compounds,  when  subjected  to  the  action  of  water 
or  alkalis,  do  not  undergo  simple  decomposition  with  the 
production  of  the  original  cellulose  and  nitric  acid,  but  give 
rise  to  complex  reactions,  which  are  very  imperfectly  known, 
and  have  been  attributed  by  some  investigators  f  to  the 
action  of  an  aldehydic  compound,  cellulose,  and  its  isomeres 
being  alcoholic  ethers  which  are  in  turn  derived  from  glucose, 
an  aldehydic  alcohol. 

When  treated,  however,  with  reducing  agents  so  as  to 
destroy  the  nitric  acid,  nitrocelluloses  are  decomposed  with 
the  reproduction  of  cellulose,  which  regains  and  retains  its 
original  properties. 

Guncotton. — Historically,  as  well  as  on  account  of  its 
great  practical  value,  guncotton  may  be  assumed  as  the  type 
of  explosive  compounds  of  the  nitric-ester  class.  As  its 
name  implies,  guncotton  is  an  explosive  made  from  cotton. 
It  is  only  necessary  to  immerse  pure  dry  cotton  in  a  mixture 

*  See  results  of  investigations  of  Van't  Hoff  and  Le  Bel. 

f  See  "  Traite  elementaire  de  Chimie  organique,"  par  Berthelot. 


208  LECTURES  ON  EXPLOSIVES. 

of  the  purest  and  strongest  nitric  and  sulphuric  acids  to  con- 
vert the  cotton  into  guncotton. 

The  purification  of  the  cotton,  the  conversion  of  the  cot- 
ton into  guncotton,  and  the  purification  of  the  guncotton  are 
all  somewhat  difficult  of  attainment,  and  hence  the  manufac- 
ture involves  some  lengthy  and  rather  complicated  processes. 

The  necessity  for  these- processes  and  their  rationale  can 
best  be  shown  by  reviewing  the  history  of  .guncotton,  for,  in 
common  with  most  of  our  modern  processes,  the  present  de- 
gree of  attainment  has  been  reached  only  through  the  labors 
and  studies,  the  failures  and  successes,  of  many  investigators. 

In  1832  Bracconot  discovered  that  when  starch,  ligneous 
fibre,  and  analogous  substances  were  treated  with  concen- 
trated nitric  acid,  a  highly  combustible  body,  which  he  termed 
xyloidine,  resulted. 

Pelouze  repeated  these  experiments  in  1838,  and  ex- 
tended his  investigations  to  cotton  and  paper,  which  he  held 
were  best  adapted  for  the  production  of  this  substance.  He 
found  that  the  body  could  be  inflamed  at  180°  C.  either  by  a 
blow  or  by  a  strong  pressure,  and  he  recommended  its  use  in 
pyrotechny.  Later,  Dumas  prepared  from  paper,  by  this 
means,  a  substance  which  he  called  nitramidine,  and  which 
he  proposed  for  use  in  making  cartridges.  The  products 
thus  obtained  were,  however,  found  to  be  irregular  in  com- 
position and  unstable,  and  so  no  practical  result  flowed  from 
these  researches,  until  late  in  1845,  when  Schoenbein  of  Basle 
announced  the  discovery  of  an  explosive,  which  he  called 
guncotton,  and  which  he  claimed  could  be  used  for  all  the 
purposes  for  which  gunpowder  was  used,  while  it  was  four 
times  as  powerful  as  the  latter.  He  kept  his  method  of 
manufacture  secret;  but  in  August,  1846,  Boettger  of  Frank- 
fort proclaimed  his  ability  to  make  guncotton,  and  on  con- 
ferring together  it  was  found  that  the  methods  employed 
were  the  same,  and  hence  the  two  formed  a  partnership  for 
disposing  of  their  secret  to  the  German  Government,  and  the 
method  remained  unpublished. 

However,  on  October  5,  1846,  Otto  of  Brunswick  gave, 


NITRIC  DERIVATIVE  EXPLOSIVE    COMPOUNDS.       2OQ 

in  the  Augsburgcr  Allgemeine  Zeitung,  a  description  of  a  proc- 
ess for  making  a  guncotton  which  closely  resembled  that  of 
Schoenbein's,  and  which  consisted  in  plunging  purified  cotton 
into  very  concentrated  nitric  acid  for  about  one-half  minute 
and  then  washing  and  drying  with  great  care,  while  nearly  at 
the  same  time  (1847)  W.  Knop  of  Hanover  and  Taylor  of 
England  discovered  that  guncotton  could  be  prepared  by 
using  mixtures  of  nitric  and  sulphuric  acids. 

These  discoveries  forced  Schoenbein  and  Boettger  to 
reveal  their  secret,  and  it  was  found  that  they  too  were  using 
the  mixed  acids,  the  proportions  being  as  follows  : 


sp.  Gr. 

Weight.      Volume. 

Nitric  acid  .........    1.45  to  1.50  I  I 

Sulphuric  acid  .....  1.85  3  2.3 

The  acids  were  mixed  in  a  porcelain  or  glass  vessel  cooled 
to  10°  or  15°  C.  Then  the  cotton  was  plunged  in,  the  pro- 
portions being  one  part  of  cotton  to  from  twenty  to  thirty  of 
the  acid.  After  about  one  hour  the  cotton  was  removed, 
washed  in  a  large  quantity  of  water,  then  in  a  solution  of 
potash  to  remove  the  last  traces  of  acid,  and,  finally,  with 
pure  water  to  remove  the  salts  which  had  been  formed.  The 
material  was  then  wrung  out,  impregnated  with  a  weak  solu- 
tion of  saltpetre,  again  wrung  out,  and  finally  dried  at  a  tem- 
perature of  65°  C. 

Taylor's  process  differed  only  in  using  one  part  of  cotton 
to  fourteen  of  the  mixed  acids. 

Heeren  and  Karmarsch  used  one  part  of  fuming  nitric 
acid  to  two  of  English  sulphuric  acid,  while  Knop  used  equal 
volumes  of  the  two  acids. 

Both  of  these  latter  allowed  the  cotton  to  remain  but 
from  four  to  five  minutes  in  the  acid. 

From  this  time  experiments  were  undertaken  in  the 
United  States,  Germany,  France,  England,  and  Russia  to 
test  the  value  of  this  explosive  as  a  substitute  for  gunpowder 
in  guns;  but  the  material  was  found  to  be  unstable,  and  gave 
rise  to  several  terrible  and  at  the  time  inexplicable  explo- 


2IO  LECTURES   ON  EXPLOSIVES. 

sions  at  Vincennes,  Bouchet,  and  Faversham  (1847-1848), 
which,  combined  with  the  grave  political  disturbances  of  the 
time,  led  to  the  discontinuance  of  the  experiments,  except 
in  Austria,  where  Baron  Von  Lenk  was  engaged  in  its  study. 

Von  Lenk's  Investigations. — From  a  consideration  of 
all  the  attending  circumstances  Von  Lenk  concluded  that  the 
accidents  above  noted  were  due  to  the  failure  to  purify  the 
cotton  perfectly;  or  to  the  use  of  too  weak  acids,  or  too 
short  an  immersion,  so  that  the  conversion  was  incomplete ; 
or  to  the  failure  to  remove  the  acids  completely  from  the 
guncotton.  The  impurities  which  are  present  in  cotton  are 
of  two  kinds,  natural  and  artificial.  The  natural  consist  of 
incrusting  matter  and  oily  matters;  the  artificial,  of  oil  and 
dirt  generally,  and  water. 

When  impure  cotton  is  immersed  in  the  acid  mixture  the 
incrusting  substance  and  greasy  matter  are  acted  upon  by  the 
acids  and  form  compounds  which  are  quite  unstable,  and 
which,  if  present  in  the  guncotton,  may  give  rise  to  decom- 
position in  the  guncotton  itself. 

The  moisture  present  serves  both  to  dilute  the  acid  mix- 
ture and  to  cause  local  heating  during  immersion,  which 
causes  waste  of  material  and  may  give  rise  to  the  formation 
of  unstable  compounds  which,  if  present  in  the  guncotton, 
may  also  provoke  spontaneous  decomposition. 

The  use  of  weak  acids  or  too  short  an  immersion  prevents 
the  complete  conversion  of  the  cotton  into  the  stable  military 
guncotton.  All  chemical  reactions  require  a  certain  time  for 
their  completion,  and  this  is  especially  the  case  when  the 
physical  structure  of  either  of  the  reacting  bodies  is  such  as 
to  prevent  rapid  contact  between  them.  The  physical  struc- 
ture of  cotton  is  such  as  to  notably  prevent  the  acids  from 
rapidly  coming  in  contact  with  its  parts,  for  it  consists  of 
long,  flat,  twisted  tubes  which  have  been  collapsed  along 
their  longitudinal  axes,  so  that  a  cross-section  presents  the 
form  of  a  figure  eight.  It  can  readily  be  understood  that  a 
considerable  time  must  elapse  before  the  acid  can  penetrate 
completely  into  the  interior  of  such  a  tube  so  as  to  convert 


NITRIC  DERIVATIVE  EXPLOSIVE   COMPOUNDS.       211 

all  its  substance  into  guncotton.  For  the  same  reason  it 
will  be  understood  that  it  must  be  very  difficult  to  expel  the 
last  traces  of  acid  from  the  capillary  tubes,  yet  if  any  trace 
of  acid  remains  in  them  it  is  likely  to  provoke  progressive 
decomposition  in  the  guncotton. 

Von  Lenk's  Process. — This  consisted  in— 

1st.  The  cleansing  and  perfect  desiccation  of  the  cotton. 
The  cleansing  was  effected  by  first  removing  the  dirt  and 
knots  by  mechanical  means,  then  immersing  the  cotton  in 
small  portions  for  two  or  three  minutes  in  a  boiling  solution 
of  caustic  potash  (sp.  gr.  1.021)  in  order  to  remove  the  fatty 
matters  and  incrusting  substances,  then  removing  the  potash 
liquor  by  means  of  a  centrifugal  machine,  and  washing  with 
pure  water  and  finally  drying  at  95°  F.  At  ordinary  tem- 
peratures cotton-wool  exposed  to  the  air  absorbs  6  per  cent 
of  moisture. 

2d.  The  employment  of  the  strongest  acids  attainable  in 
commerce.  These  consisted  of  nitric  acid  sp.  gr.  1.48  to  1.49 
at  1 7°. 5  C.  and  sulphuric  acid  sp.  gr.  1.835,  mixed  in  the 
proportions  of  one  part  by  weight  of  nitric  to  three  parts  by 
weight  of  sulphuric. 

3d.  The  steeping  of  the  cotton  in  a  fresh  strong  mixture  of 
acids,  after  its  first  immersion  and  partial  conversion  into 
guncotton.  A  pot  holding  about  60  pounds  of  the  acid  mix- 
ture was  used  for  the  dipping,  and  two  skeins  (about  3 
ounces)  of  cotton  were  dipped  at  each  operation.  After 
some  minutes  the  partially  converted  cotton  was  removed 
from  the  pot,  placed  upon  a  rack,  and  squeezed  until  one  part 
of  the  cotton  contained  about  ten  and  one  half  parts  of  acid. 
The  pressed  cotton  was  now  placed  in  a  steeping-pot  and 
fresh  acid  poured  over  it,  while  the  dipping-pot  was  filled  to 
its  original  level  with  acid. 

4th.  The  continuance  of  the  steeping  for  twenty -four  to 
forty-eight  hours.  After  the  guncotton  had  been  placed  in 
the  steeping-pot  and  the  acid  added,  the  guncotton  was  pressed 
to  the  bottom  of  the  pot,  so  that  it  would  be  completely  cov- 
ered with  the  acid,  the  pot  was  then  covered,  placed  in  a 


212  LECTURES   ON  EXPLOSIVES. 

trough  of   cool  water   and   allowed    to    remain  for   the   time 
stated. 

5th.  The  thorougli  purification  of  the  guncotton  so  produced 
from  every  trace  of  free  acid.  To  effect  this  the  guncotton 
was  placed  in  a  centrifugal  machine,  revolving  at  about  800 
turns  per  minute,  and  in  about  ten  minutes  the  acid  present 
was  reduced  so  that  about  one  pound  of  the  guncotton  con- 
tained but  three  pounds  of  acid. 

The  guncotton  was  then  plunged  into  a  cascade  of  water 
and  washed  in  a  running  stream  of  water  for  from  three  to 
six  weeks,  and  then  treated  with  a  weak  solution  of  boiling 
potash,  washed  and  dried  in  free  air  at  25°  C.  Then  the 
guncotton  was  immersed  for  some  time  in  a  solution  of 
sodium  silicate  (sp.  gr.  1.072),  wrung,  and  exposed  for  three 
days  to  free  air,  again  washed,  wrung  and  dried,  first  in  free 
air,  and  finally  in  a  chamber  whose  temperature  did  not 
exceed  35°  C. 

Von  Lenk  began  the  manufacture  at  Heitenberg,  near 
Wiener-Neustadt,  about  1853,  and  continued  to  direct  the 
factory  up  to  1865,  during  which  time  considerable  quantities 
of  the  material  were  made.  Extensive  experiments,  on  its 
value  as  a  substitute  for  gunpowder  as  a  projecting  agent, 
were  conducted  with  it,  and  the  results  were  so  favorable  that 
the  Austrians  supplied  thirty  batteries  with  guncotton  car- 
tridges, and  the  explosive  bid  fair  to  soon  be  adopted  as  a 
service  explosive ;  but,  unfortunately,  two  serious  explosions 
during  storage  occurred,  one  at  the  magazine  at  Simmering 
in  1862,  the  other  at  the  magazine  of  Steinfeld  in  1865, 
and  these  combined  with  the  fact  that  the  explosive,  in  spite 
of  the  precautions  taken,  often  developed  abnormal  pressures 
in  the  guns  led  to  its  use  being  interdicted. 

Abel's  Improvements  and  Patents. — Von  Lenk  patented 
his  process  in  England  in  1862,  and  in  1864  the  Prentice 
Brothers  began  the  manufacture  of  guncotton  under  this 
process  at  Stowmarket. 

In  1865  Abel  patented  his  improvement  on  the  process. 
This  consisted  in  reducing  the  guncotton  to  a  pulp,  and  then 


NITRIC  DERIVATIVE  EXPLOSIVE   COMPOUNDS.       213 

by  moulding  and  pressure  converting  it  into  such  forms  and 
masses  as  were  desired  for  use.  The  pulping  was  effected  by 
a  rag-engine  or  pulper,  such  as  is  used  in  converting  the  rags 
used  in  making  paper  into  pulp. 

The  advantage  gained  by  this  is,  first,  that  the  guncotton 
tubes  are  cut  into  such  short  lengths  that  the  acid  and  for- 
eign matters  can  be  easily  and  completely  removed  from  the 
fibre ;  second,  that  cotton  waste,  a  cheaper  material,  can  be 
used  for  the  manufacture ;  and  third,  since  the  pulped  mate- 
rial can  be  pressed,  it  is  possible  to  impart  to  the  final  prod- 
uct a  high  density  and  thus  obtain  a  large  weight  of  the 
explosive  in  a  small  volume. 

Abel's  modifications  were  shortly  afterwards  adopted  at 
Stowmarket,  and  the  manufacture  and  use  were  successfully 
pursued  without  accident  until  August,  1871,  when  1 3 \  tons  of 
the  compressed  guncotton  which  were  stowed  in  the  packing- 
house at  Stowmarket  exploded.  A  very  thorough  investiga- 
tion of  the  circumstances  attending  this  explosion  was  made, 
and  as  a  result  the  jury  found  "  that  the  accident  was  due  to 
the  spontaneous  explosion  of  some  impure  guncotton,  the  im- 
purity consisting  in  the  presence  of  a  large  quantity  of  sulphuric 
acid,  or  of  mixed  sulphuric  and  nitric  acids,  which  acids  were 
wilfully  added  by  some  person  or  persons  unknown,  after  the 
guncotton  had  passed  through  the  regular  process  of  manu- 
facture and  testing."  Since  then  we  have  no  record  of  any 
spontaneous  explosions  having  occurred,  and  it  is  very  unlikely 
that  they  should  have  taken  place,  for,  thanks  to  Brown's 
discovery,  the  finished  product  is  now  almost  wholly  stored 
in  the  wet  state.  Shortly  after  the  Stowmarket  explosion  the 
English  Government  erected  works  at  Waltham  Abbey,  and 
the  French  at  Moulin-Blanc,  and  the  other  European  govern- 
ments followed  suit,  all  of  them  adopting  Von  Lenk's  process 
with  Abel's  modifications. 

Adoption  of  Guncotton  in  this  Country  as  a  Service 
Explosive. — As  has  been  said  above,  experiments  were  made 
in  this  country,  not  long  after  the  discovery  of  guncotton,  to 
test  its  value  as  a  projecting  charge  in  guns,  but  they  were 


214  LECTURES   ON  EXPLOSIVES. 

soon  abandoned,  as  the  material  was  found  to  be  too  unsafe 
for  use  in  this  way. 

Experiments  were,  however,  begun  at  the  U.  S.  Torpedo 
Station  by  Professor  Hill  in  1872  to  test  the  value  of  the  com- 
pressed guncotton,  as  made  by  Abel's  process,  for  the  use  of 
the  torpedo  service,  and  the  experiments  were  continued  up  to 
1883,  and  on  November  14  of  that  year  a  guncotton  torpedo 
outfit  was  issued  to  the  U.  S.  S.  Trenton  and  the  material, 
was  adopted  as  a  service  explosive  in  the  United  States  Navy. 

The  guncotton  used  in  these  experiments  was  obtained 
from  Stowmarket,  and  that  issued  to  the  Trenton  was  in  the 
form  of  cylindrical  disks  three  inches  in  diameter  and  two 
inches  high. 

Guncotton  having  been  adopted  as  a  service  explosive,  it 
was  not  deemed  prudent  to  depend  upon  foreign  sources  for 
our  supply ;  a  plant  for  the  manufacture  of  the  explosive  was 
therefore  installed  at  the  U.  S.  Naval  Torpedo  Station,  and 
the  manufacture  of  gun-cotton  was  began  early  in  1884,  and 
continued  in  successful  operation  until  the  factory  was  de- 
stroyed by  fire  in  1893.  This  factory  has  been  restored,  and, 
together  with  the  DuPont  plant,  continues  to  supply  the 
highest  grade  of  guncotton  in  such  quantities  as  to  meet  all 
demands.* 

Chemistry  of  Guncotton. — From  its  reactions  cellulose 
may  be  regarded  as  an  alcohol,  but  owing  to  the  fact  that  cel- 
lulose is  a  non-volatile  solid,  its  vapor  density,  and  therefore 
its  molecular  weight,  has  never  been  determined,  and  conse- 
quently its  molecular  constitution  is  unknown.  Its  ultimate 
analysis,  however,  leads  to  the  simplest  empirical  formula  of 
C6H10O5 ,  but  it  is  probable  that  its  true  molecular  constitution 
should  be  represented  by  some  multiple  of  this  expression. 

When  cellulose  is  acted  upon  by  nitric  acid  or  mixtures  of 
nitric  and  sulphuric  acids,  the  hydrogen  of  the  hydroxyl  is 
replaced,  more  or  less  completely,  by  NO, ,  and  in  this  way 
various  cellulose  nitrates  may  be  obtained.  The  composition 

*  The  American  Smokeless    Powder  Co.  is  now  producing  an  excellent 
grade  of  guncotton  which  is  fully  up  to  the  highest  standard. 


NITRIC  DERIVATIVE  EXPLOSIVE    COMPOUNDS.       21 5 

of  the  products  resulting  from  this  action  depends  upon  the 
strength  of  the  acids  employed,  the  proportions  of  acid  used, 
the  temperature  during  immersion,  and  the  time  of  immersion. 
If  the  acids  are  as  follows: 

Sp.  Gr.  Parts  by  Weight. 

HNO3 1.50  I 

HaS04 1.85  3 

— the  proportions  of  cellulose  to  acid  is  as  I  :  300,  the  time  of 
immersion  ten  minutes,  the  time  of  steeping  forty-eight  hours, 
and  the  temperature  about  15°  C.  ;  then  we  ought  to  obtain 
the  most  complete  conversion  of  the  cellulose,  and,  if  we 
assume  the  lowest  multiple  of  the  above  expression  to  repre- 
sent the  composition  of  cellulose,  the  reaction  would  be  ex- 
pressed by  the  following  equation,  GBH7O2(OH)3  -f  3HO. 
NO,  =  (C6H7O4)O3(NOa)3-f  3H2O.  The  cellulose  thus  ob- 
tained is  familiarly  known  as  "  tri-nitrocellulose, "  and,  accord- 
ing to  Abel,  it  is  the  principal  constituent  of  the  military 
guncotton.  Theoretically,  100  parts  of  cellulose  should  yield 
when  properly  nitrated  183.5  parts  of  tri-nitrocellulose;  prac- 
tically, the  yield  is  about  155  parts  of  explosive  from  every  100 
parts  of  thoroughly  dried  cotton. 

In  his  investigation  Eder  discovered  a  form  of  nitrocellu- 
lose in  which  the  percentage  of  nitrogen  lay  between  that 
contained  in  the  di-nitro-  and  tri-nitro-compounds.  He 
therefore  assumed  the  formula  for  cellulose  to  be  CiaH20OB , 
but  failed  to  obtain  or  recognize  the  mono-nitro-derivative. 

Vieille  carried  his  investigations  even  further,  and  obtained 
various  forms  of  nitrocellulose  under  extremely  different  con- 
ditions, and,  as  a  result  of  his  experiments,  assumed  a  still 
higher  multiple  of  C8H10OB ,  namely,  C24H<0O20 ,  as  the  con- 
stitutional formula  for  cellulose.  Although  the  mono-nitro- 
derivative  has  never  been  obtained  alone,  it  appears  to  be 
formed  in  connection  with  the  higher  nitro-compounds  during 
the  process  of  nitration.  The  various  forms  of  nitro-cellulose 
together  with  the  percentage  of  nitrogen  in  each,  may  there- 
fore be  enumerated  as  follows: 


216 


LECTURES  ON  EXPLOSIVES. 


mono-nitrocellulose  with 
di-nitrocellulose     " 
tri-nitrocellulose     " 


7.34  per  cent  of  N 

11.13  "      "     "  " 

14.14  "      "     "  " 


di-nitrocellulose  with    6.76  per  cent  of  N 

tri-nitrocellulose     "       9.15  "       "     "  " 

tetra-nitrocellulose     "     ii.n   "       "     "  " 

penta-nitrocellulose     "     12.75   "       "     "  " 

hexa-nitrocellulose     "     14.14  "       "     "  " 


tetra-nitrocellulose 

with    6.76  per  cent  of  ] 

penta-nitrocellulose 

"       8 

02    "         "      " 

hexa-nitrocellulose 

"       9- 

15    "       " 

• 

hepta-nitrocellulose 

"     10 

18    " 

1 

octo-nitrocellulose 

"     n. 

ii 

1 

mono-nitrocellulose 

"     ii. 

96 

' 

«- 

deca-nitrocellulose 

"      12. 

75 

' 

•€ 

ndeca-nitrocellulose 

"     I3- 

47 

' 

odeca-  nitrocellulose 

"     J4- 

14     ' 

From  C8H10O5, 

(CaH702)03(N02)H2 
(C6H709)0,(NOa)aH 
(C(5H703)03(N02)3 

From  C12H20O]0 , 

(CiaH1404)08(N02)2H4  = 

(C12H1404)06(N02)3H3  = 

(C12H1404)08(N02)4H2  = 

(C12H1404)06(N02)5H  = 
(CJ2H1404)06(NO,)8 

From  C34H40O20> 

(C24H2808)012(NO,)4H8  = 
(C24H2808)012(N02)5H7  = 
(C24H2808)012(N02)6H9  = 
(C24H2808)0I2(N02)7H6  = 
(C24H2808)012(N02)8H4  = 
(C24H2808)012(N02)9H3  = 
(C24H2808)012(N02)10H2  = 
(C24H2808)012(N02)11H  = 
(C24H2808)012(N02)12  = 

The  highest  grades  of  nitrocellulose  are  obtained  only  by 
using  the  purest  and  most  concentrated  acids,  and  by  subject- 
ing the  cellulose,  which  must  be  thoroughly  cleaned  and  dried 
beforehand,  to  the  action  of  the  acids  for  a  considerable  length 
of  time.  The  highest  degree  of  nitration  of  which  cellulose  is 
susceptible,  or,  in  other  words,  the  highest  grade  of  cellulose 
nitrate  obtainable,  depends  upon  the  formula  assumed  to  rep- 
resent the  original  cellulose.  There  appears  to  be  no  doubt 
that  a  nitrate  of  cellulose  may  be  produced  containing  a  higher 
percenisige  of  nitrogen  than  can  possibly  exist  in  the  most 
highly  nitrated  product  obtainable  from  cellulose  represented 
by  Vieille's  formula.  The  weight  of  evidence  points  to  C18H21 
O6(OH)B  or  some  higher  multiple  than  4(C6H10O5)  as  the  most 
probable  constitution  of  cellulose.  The  lower  grades  of  nitro- 
cellulose are  prepared  by  using  weaker  acids  or  other  modifi- 
cations in  the  process  of  nitration. 

The  tri-nitrocellulose  of  Abel,  which  corresponds  exactly 
with  Eder's  hexa-nitrate  and  the  deca-  and  endeca-nitrates  of 
Vieille,  are  known  as  military  guncotton,  and  are  characterized 


NITRIC  DERIVATIVE  EXPLOSIVE   COMPOUNDS.       2\J 

by  their  insolubility  in  the  ether-alcohol  mixture  (one  volume 
of  absolute  alcohol,  sp.  gr.  0.805,  to  two  volumes  of  strongest 
ether,  sp.  gr.  0.735);  the  endeca-nitrocellulose  is,  however, 
completely  dissolved  by  ethyl  acetate.  Of  the  other  cellulose 
nitrates,  the  di-,  octo-,  and  mono-nitro-compounds  are  readily 
soluble  in  the  ether-alcohol  mixture  as  well  as  in  ethyl  acetate 
(acetic  ether) ;  the  hepta-nitrate,  when  treated  with  these  sol- 
vents, gelatinizes,  but  does  not  dissolve  entirely;  of  the  other 
derivatives  of  Vieille,  subjected  to  the  action  of  the  same 
agents,  the  hexa-nitrate  swells  up  without  dissolving  in  ethyl 
acetate,  and  is  unaffected  by  the  mixture,  while  the  penta- 
and  tetra-nitrates  are  scarcely  affected.  As  has  been  said,  the 
tri- nitrocellulose  of  Abel,  the  hexa-nitrocellulose  of  Eder, 
and  the  deca-  and  endeca-nitrocelluloses  of  Vieille  are  known 
as  guncotton,  while  the  other  cellulose  nitrates  are  known  as 
pyroxyline  and  collodion  guncotton. 

Collodion  guncotton  is  so  called  from  the  fact  that  the 
solution  which  it  forms  with  ether-alcohol,  when  exposed  to 
the  air,  gives  up  its  ether  and  alcohol  by  volatilization  and  de- 
posits its  guncotton  as  a  gummy,  collodial,  strongly  adhesive 
film  on  the  body  with  which  it  is  contact.  This  solution, 
known  as  collodion,  is  employed  for  coating  the  surfaces  of 
the  plates  used  in  the  wet  process  of  photography,  and  it  is 
also  used  in  surgery  to  produce  an  artificial  skin  over  cuts  and 
wounds. 

Properties  of  Guncotton. — The  fibrous  guncotton  seen 
in  ordinary  light  differs  little,  if  any,  in  appearance,  even  when 
examined  under  a  microscope,  from  the  cotton  from  which  it 
is  made,  but,  if  seen  under  the  microscope  by  polarized  light, 
the  fibres  of  guncotton  appear  dull  and  only  feebly  colored, 
while  cotton  fibres,  under  the  same  circumstances,  are  brilliant 
in  lustre  and  iridescent. 

Guncotton  is  harsher  to  the  touch  and  less  flexible  than 
cotton  ;  when  dry  it  becomes  quite  highly  electrified  if  rubbed 
between  the  fingers,  and  is  luminous  when  rubbed  in  the  dark. 

Guncotton  is  completely  insoluble  in  water,  either  hot  or 
cold. 


21 8  LECTURES   ON  EXPLOSIVES. 

The  action  of  ethyl  acetate  and  of  ether-alcohol  upon  it  and 
the  pyroxylins  has  been  noted  above. 

Guncotton  is  also  soluble  in  a  mixture  of  ether  and  ammo- 
nia and  in  acetone  [(CH3)aCO].  All  the  cellulose  nitrates  are 
soluble  in  a  strong  solution  of  sodium  hydroxide,  undergoing 
a  partial  saponification,  with  the  formation  of  cellulose  and 
sodium  nitrate.  Concentrated  sulphuric  acid  displaces  the 
nitric  acid  even  in  the  cold.  Reducing  agents,  such  as  ferrous 
chloride  or  acetate,  or  the  alkaline  sulphyroxides,  especially 
in  alcoholic  solution,  convert  the  cellulose  nitrates  into  cellu- 
lose, even  by  digestion  at  ordinary  temperatures.  By  boiling 
with  a  solution  of  stannous  oxide  in  potassium  hydroxide  the 
cellulose  nitrates  are  dissolved  and  the  cellulose  is  reduced  and 
may  be  precipitated  in  flocks  on  neutralizing  the  liquid.  These 
reactions  are  often  employed  in  the  analysis  of  the  cellulose 
nitrates.  The  density  of  guncotton  varies  with  the  mode  of 
preparation  and  the  amount  of  compression  to  which  it  is  sub- 
jected. It  averages  about  o.  I  to  0.3  for  guncotton  in  the 
form  of  flocks  or  fibre,  and  is  about  1. 1  for  the  dry  compressed 
Abel  guncotton.  Experiments  made  at  L'Ecole  de  Pyro- 
technic de  Toulon  (i  870)  showed  that  the  pressure  to  be  applied 
increases  much  more  rapidly  than  the  density  of  the  resulting 
product,  and  that  it  is  impracticable  to  carry  the  density  above 
1.4  to  1.5. 

Guncotton  is  said  to  be  less  hygroscopic  than  either  ordi- 
nary cotton  or  than  gunpowder.  The  normal  humidity  of 
air-dry  guncotton  is  put  at  1.5  to  2  per  cent,  though  it  is 
believed  that  by  prolonged  exposure  to  a  saturated  atmos- 
phere it  may  reach  2.75  per  cent,  but  this  does  not  appear 
to  have  any  marked  effect  on  its  inflammability.  According 
to  Beckerhinn  an  increase  in  the  percentage  of  moisture  in 
guncotton  used  for  projecting  charges  causes  a  more  rapid  fall 
in  the  pressure  produced  than  in  the  initial  velocities  given, 
which,  if  true,  gives  a  means  for  neutralizing  the  brisant  effect 
of  guncotton  on  the  piece,  while  leaving  us  a  ballistic  medium 
much  superior  in  power  to  ordinary  gunpowder. 

It  is  claimed  that  guncotton  is  not  susceptible,  even  when 


NITRIC  DERIVATIVE  EXPLOSIVE   COMPOUNDS.       2IQ 

dry,  to  pressure,  percussion,  or  friction,  unless  it  be  strongly 
confined  and  firmly  compressed,  and  the  heat  developed  is 
very  considerable,  but  experiments  in  this  laboratory  tend  to 
disprove  this  claim. 

To  explode  dry  guncotton  by  percussion  with  some 
degree  of  certainty,  it  is  necessary  to  take  a  very  small  piece, 
wrap  it  tightly  in  tin-foil,  place  it  on  an  anvil,  strike  it  sev- 
eral light  blows  to  compress  it,  and  then  a  heavy  blow.  If 
the  latter  is  not  fair  it  will  fail  to  effect  the  result.  As  will 
be  seen  later,  shell  filled  with  disks  of  dry  guncotton  have 
been  fired  from  24-pounders  with  service  charges  of  powder 
into  the  masonry  escarpment  of  the  fort  on  Rose  Island  at  a 
distance  of  50  yards  from  the  muzzle  of  the  gun,  where  the 
shell  were  completely  broken  up  on  impact  without  any  of 
the  guncotton  having  been  exploded. 

The  wet  guncotton  is  in  the  process  of  pressing  subjected 
to  a  pressure  of  about  6300  pounds  per  square  inch ;  and  the 
pressure  has  been  carried  to  over  13,000  pounds  without 
causing  explosion. 

If  a  flame  or  any  incandescent  body  is  applied  to  dry  loose 
guncotton,  the  latter  burns  with  a  flash  but  without  explosion. 
If  the  guncotton  is  woven  or  twisted  tightly,  the  speed  of 
combustion  is  very  much  reduced,  and  when  the  guncotton  is 
pulped  and  compressed,  the  rate  of  combustion  is  reduced 
still  more.  If  water  is  poured  on  a  disk  or  block  of  burning 
guncotton,  the  flame  may  be  extinguished,  though  sometimes, 
when  the  fire  is  inside,  it  can  be  reached  only  with  difficulty. 

If  the  mass  of  burning  guncotton  is  very  large,  it  is  pos- 
sible that  an  explosion  may  take  place  from  the  outer  parts 
furnishing  sufficient  confinement  to  the  inner. 

Wet  compressed  guncotton  cannot  be  set  on  fire  until  the 
moisture  is  dried  out  of  it.  If  a  wet  disk  or  block  be  placed 
in  a  fire,  the  outer  surface  will  dry  and  be  slowly  consumed, 
and  this  will  continue,  layer  by  layer,  until  the  whole  is  con- 
sumed. As  much  as  2000  pounds  of  wet  guncotton  has  been 
placed  in  a  bonfire,  where  it  slowly  burned  away  without 
explosion.  The  point  of  explosion  of  guncotton  and  py- 


22O  LECTURES   ON  EXPLOSIVES. 

roxylin  naturally  vary  somewhat,  but  that  of  guncotton  may 
be  taken  as  about  182°  C.  (360°  F.). 

Considerable  apprehension  exists  in  the  minds  of  many 
who  are  not  intimately  acquainted  with  the  substance,  re- 
garding guncotton,  and  they  are  apt  to  fear  that,  through 
decomposition  during  storage  or  transportation,  or  by  the  ac- 
tion of  ordinary  shocks,  heat,  or  pressure,  it  may  accidentally 
explode. 

These  apprehensions  have  arisen  from  the  many  accidents 
which  have  occurred  in  the  history  of  the  explosive,  some  of 
which  have  been  noticed  already,  and  which,  as  has  been 
pointed  out,  were  due  to  the  impurities  existing  in  the  gun- 
cotton  as  a  necessary  result  of  the  imperfect  processes  of 
manufacture  followed,  and  these  apprehensions  are  strength- 
ened by  the  many  accidents  which  have  occurred  in  the  past, 
and  still  do  occur,  with  other  high  explosives,  and  which  many 
appear  to  think  are  a  necessary  consequence  of  their  use. 

While  guncotton  is  a  powerful  explosive,  and  in  fact  a 
high  explosive,  and  necessarily  dangerous,  as  all  explosives 
must  be ;  yet  when  handled,  used,  and  stored  as  directed,  it 
is  the  safest  explosive  known,  and  when  properly  made  is 
absolutely  free  from  any  tendency  to  undergo  dangerous 
decomposition. 

Decomposition  of  Guncotton. — When  guncotton  is  de- 
composing it  first  begins  to  give  off  nitrous  fumes,  and 
eventually  yields  them  in  such  quantity  as  to  color  the  sur- 
rounding atmosphere  a  deep  brownish  red.  At  the  same 
time  the  guncotton  begins  to  show  pasty  yellow  spots,  and 
eventually  the  whole  becomes  converted  into  a  pasty  yellow 
mass,  which  first  shrinks  to  about  one  tenth  of  the  volume  of 
the  original  guncotton,  and  then  swells  up  as  the  gas  is  evolved. 
Next  the  mass  shrinks  again,  and  becomes  converted  into  a 
gummy  residue  having  a  very  much  smaller  volume  than  the 
guncotton  from  which  it  was  formed,  and  finally  it  dries  up 
to  a  brown  horn-like  mass. 

This  decomposition  results  in  the  formation  from  the  gun- 
cotton  of  oxides  of  nitrogen,  formic  and  acetic  acids,  which 


NITRIC  DERIVATIVE   EXPLOSIVE    COMPOUNDS.       221 

are  evolved  as  vapors,  and  an  amorphous,  porous,  sugar-like 
body  almost  entirely  soluble  in  water,  which  contains  a  con- 
siderable quantity  of  glucose,  gummy  matter,  and  oxalic  acid, 
and  a  small  quantity  of  formic  acid,  and  of  pectic  and  para- 
and  meta-pectic  acids.  Changes  such  as  these  just  described 
have  repeatedly  taken  place  under  my  own  observation  with 
guncotton  which  has  been  imperfectly  freed  from  acid,  or 
with  pyroxylin,  and  many  other  chemists  have  observed 
them,  and  in  none  of  these  cases  did  an  explosion,  or  any- 
thing approaching  an  explosion,  take  place. 

The  decomposing  effects  of  acids  may  also  be  witnessed  at 
the  U.  S.  Naval  Torpedo  Station  on  any  Saturday  while  the 
guncotton  factory  is  in  operation,  for  it  is  the  custom  at  that 
time  to  take  the  waste  sweepings  of  the  factory,  which  have 
accumulated  during  the  week,  to  the  beach,  and  to  pour  upon 
them  a  quantity  of  the  waste  acid  mixture. 

Soon  after  the  acid  is  poured  on  the  mass  begins  to  yield 
copious  quantities  of  oxides  of  nitrogen  (or,  as  the  workmen 
technically  say,  "  firing"  takes  place)  and  the  mass  undergoes 
the  changes  described  above,  but  no  explosion  ensues.  These 
observations  have  been  made  on  guncotton  decomposing 
when  unconfined  or  when  loosely  confined.  It  is  of  course 
obvious  that  if  the  guncotton  was  confined  in  a  tight  recepta- 
cle the  gases  evolved  during  decomposition  might  generate 
pressure  enough  to  burst  the  receptacle  and  thus  produce  an 
explosion. 

Again,  as  heat  is  produced  by  the  chemical  reaction,  it 
might  be  possible  that  when  the  guncotton  is  confined  the 
heat  generated  cannot  be  conveyed  away  as  fast  as  generated, 
and  that  in  consequence  the  temperature  continually  in- 
creases so  that  it  eventually  reaches  the  ignition-point  of  the 
explosive;  then,  of  course,  an  explosion  might  ensue :  and  this 
is  the  probable  explanation  of  the  origin  of  the  explosions 
noted  as  occurring  in  the  magazines  at  Stowmarket  and  else- 
where. The  decompositions  described  have,  with  the  excep- 
tion of  the  destruction  of  the  waste  at  this  station,  been 
observed  to  take  place  only  in  dry  guncotton  or  pyroxylin. 


222  LECTURES   ON  EXPLOSIVES. 

To  produce  it  in  wet  guncotton  it  is  necessary  that  the 
amount  of  acid  present  should  be  very  much  in  excess  of  the 
guncotton  with  which  it  is  in  contact ;  hence  the  development 
of  such  slight  traces  of  acid  during  the  storage  of  wet  com- 
pressed guncotton  as  have  been  observed  by  Abel  is  not 
likely  to  produce  dangerous  decomposition,  while,  besides,  the 
water  present  tends  to  prevent  any  considerable  rise  in  tem- 
perature. 

It  is  well  known  that  light  rays  sometimes  play  an  impor- 
tant part  in  inducing  chemical  changes.  We  have  only  to 
cite  the  well-known  cases  of  the  decomposition  of  carbon 
dioxide  within  the  leaf-cells  of  plants,  or  of  the  silver  salts 
in  the  photographic  plate,  or  better,  in  this  connection,  the 
decomposition  of  the  amides.  It  is  not  to  be  wondered  at 
that  it  should  be  believed  and  expected  that  guncotton 
would  also  be  susceptible  to  the  action  of  light,  especially 
since  Tyndall  has  shown  that  nitrous  esters  like  the  amyl  and 
butyl  nitrites  may  be  decomposed  by  the  action  of  a  beam  of 
light.  The  literature  of  guncotton  and  pyroxylin  is  full  of 
the  most  conflicting  statements  regarding  the  effect  of  light 
upon  them,  but  this  is  not  surprising  when  we  consider  the 
great  variety  of  substances  employed  and  their  varying  de- 
grees of  purity  as  made  by  different  methods.  Guncotton 
produced  from  properly  purified  cotton,  according  to  the 
directions  given  by  Von  Lenk,  may  be  exposed  to  diffused 
daylight,  either  in  open  air  or  in  closed  vessels,  for  very  long 
periods  without  undergoing  any  change. 

The  preservation  of  the  material  for  three  and  one-half 
years  under  these  conditions  has  been  perfect.  Long-con- 
tinued exposure  of  the  substance,  in  a  condition  of  ordinary 
dryness,  to  strong  daylight  and  sunlight  produces  a  very 
gradual  change  in  guncotton  of  the  description  defined  above ; 
and  the  statements  which  have  been  published  regarding  the 
very  rapid  decomposition  of  guncotton  when  exposed  to  sun- 
light do  not  therefore  apply  to  the  nearly  pure  cellulose  nitrate 
obtained  by  strictly  following  the  system  of  manufacture  now 
adopted.  If  guncotton  in  closed  vessels  is  left  for  protracted 


NITRIC  DERIVATIVE   EXPLOSIVE    COMPOUNDS.       22$ 

periods  exposed  to  strong  daylight  and  sunlight  in  a  moist  or 
damp  condition  it  is  affected  to  a  somewhat  greater  extent; 
but  even  under  these  circumstances  the  change  produced  in 
the  guncotton  by  several  months'  exposure  is  of  a  very  trifling 
nature. 

Singularly  enough  it  has  been  found  that  guncotton  which 
had  been  freely  exposed  to  air  and  diffused  sunlight  for  about 
twelve  months  had  its  stability,  as  determined  by  the  heat 
test,  very  materially  raised.  Guncotton  which  is  exposed 
to  sunlight  until  a  faint  acid  reaction  has  become  developed, 
and  is  then  immediately  afterwards  packed  in  boxes  which  are 
tightly  closed,  does  not  undergo  any  change  during  subse- 
quent preservation  in  ordinary  storehouses  (as  far  as  an  ex- 
perience of  three  and  one-half  years  has  shown).  Guncotton 
prepared  and  purified  according  to  the  prescribed  system  and 
stored  in  the  ordinary  dry  condition  does  not  furnish  any 
indication  of  alteration  beyond  the  development,  shortly  after 
it  is  first  packed,  of  a  slight  peculiar  odor,  and  the  power  of 
gradually  imparting  to  litmus,  when  packed  with  it,  a  pink 
tinge. 

Abel  has  studied  the  effects  of  heat  upon  both  dry  and  wet 
guncotton,  and  he  finds  that  the  influence  exerted  upon  the 
stability  of  guncotton  of  average  quality,  as  obtained  by  strict 
adherence  to  Von  Lenk's  system  of  manufacture,  by  prolonged 
exposure  to  temperatures  considerably  exceeding  those  which 
are  experienced  in  tropical  climates  is  very  trifling,  and  it  may 
be  so  perfectly  counteracted  by  very  simple  means,  which  in 
no  way  interfere  with  the  essential  qualities  of  the  material, 
that  the  storage  and  transportation  of  guncotton  presents  no 
greater  danger,  and  is,  under  some  circumstances,  attended 
with  much  less  risk  of  accident,  than  is  the  case  with  gunpow- 
der. Perfectly  pure  guncotton  resists  to  a  remarkable  extent 
the  destructive  effects  of  temperatures,  even  those  approaching 
100°  C.,  and  the  lower  cellulose  nitrates  (soluble  guncotton  or 
pyroxylin)  are  at  any  rate  not  more  prone  to  alteration  when 
pure.  The  incomplete  conversion  of  cotton  into  the  most 
explosive  product  does  not,  therefore,  of  necessity  result  in 


224  LECTURES   ON  EXPLOSIVES. 

the  production  of  a  less  perfectly  permanent  compound  than 
that  obtained  by  the  most  perfect  action  of  the  acid  mixture. 

But  all  ordinary  products  of  manufacture  contain  small 
proportions  of  organic  nitrogenized  impurities  of  compara- 
tively unstable  properties,  which  have  been  formed  by  the 
action  of  nitric  acid  upon  foreign  matters  retained  by  the 
cotton  fibre,  and  which  are  not  completely  separated  by  the 
ordinary  or  even  a  more  searching  process  of  purification. 

It  is  the  presence  of  this  class  of  impurities  in  guncotton 
which  first  give  rise  to  the  development  of  free  acid  when  the 
substance  is  exposed  to  the  action  of  heat ;  and  it  is  the  acid 
thus  generated  which  eventually  exerts  a  destructive  action 
upon  the  cellulose  products,  and  thus  establishes  decomposi- 
tion which  is  materially  accelerated  by  heat.  If  the  small 
quantity  of  acid  developed  by  the  impurity  in  question  be 
neutralized  as  it  becomes  nascent  no  injurious  action  upon 
the  guncotton  results,  and  the  great  promoting  cause  of  the 
decomposition  of  guncotton  by  heat  is  removed. 

This  result  is  readily  attained  by  uniformly  distributing 
through  guncotton  a  small  proportion  of  a  carbonate,  the 
sodium  carbonate  applied  in  the  form  of  a  solution  being 
best  adapted  to  this  purpose.  The  introduction  into  finished 
guncotton  of  one  per  cent  of  sodium  carbonate  affords  to  the 
material  the  power  of  resisting  any  serious  change,  even  when 
exposed  to  such  elevated  temperatures  as  would  induce  some 
decomposition  in  the  perfectly  pure  cellulose  products.  That 
proportion  affords,  therefore,  security  to  guncotton  against 
any  destructive  effects  of  the  highest  temperatures  to  which 
it  is  likely  to  be  exposed,  even  under  very  exceptional  climatic 
conditions.  The  only  influences  which  the  addition  of  that 
amount  of  carbonate  to  guncotton  might  exert  upon  its  prop- 
erties as  an  explosive  would  consist  of  a  trifling  addition  to 
the  small  amount  of  smoke  attending  its  combustion,  and  in 
a  slight  retardation  of  its  explosion,  neither  of  which  could 
be  regarded  as  results  detrimental  to  the  probable  value  of 
the  material. 

It  has  been  observed  that  when  dry  guncotton  is  freely 


NITRIC  DERIVATIVE   EXPLOSIVE   COMPOUNDS.       22$ 

exposed  to  air  in  an  atmosphere  of  a  temperature  of  about 
45°  C.  for  about  three  months,  its  stability,  as  determined  by 
the  heat  test,  is  materially  raised — just  as  Abel  found  it  to  be 
for  exposure  to  diffused  daylight. 

Water  acts  as  a  most  perfect  protection  to  guncotton  (ex- 
cept when  it  is  exposed  to  sunlight)  even  under  extremely 
severe  conditions  of  exposure  to  heat.  An  atmosphere  satu- 
rated with  aqueous  vapor  suffices  to  protect  it  from  change 
at  elevated  temperatures,  and  wet  or  damp  guncotton  may  be 
exposed  for  long  periods  in  confined  spaces  at  100°  C.  with- 
out sustaining  any  change.  Actual  immersion  in  water  is  not 
necessary  for  the  most  perfect  preservation  of  guncotton ;  the 
material,  if  only  damp  to  the  touch,  sustains  not  the  slight- 
est change  even  if  closely  packed  in  large  quantities.  The 
organic  impurities  which  doubtless  give  rise  to  the  very  slight 
development  of  acid  when  guncotton  is  closely  packed  in  the 
dry  condition  appear  equally  protected  by  the  water,  for 
damp  and  wet  guncotton  which  has  been  preserved  for  three 
years  has  not  exhibited  the  faintest  acidity.  If  as  much 
water  as  possible  be  expelled  from  the  guncotton  by  the  cen- 
trifugaV  extractor,  it  is  obtained  in  a  condition  in  which, 
though  only  damp  to  the  touch,  it  is  perfectly  non-explosive; 
the  water  thus  left  in  the  material  is  sufficient,  not  only  to 
act  as  a  perfect  protective,  but  also  to  guard  against  all  risk 
of  accident. 

It  is  therefore  in  this  wet  condition  that  all  reserve  stores 
of  the  substance  should  be  preserved,  or  that  it  should  be 
transported  in  large  quantities.  If  the  proper  proportion  of 
sodium  carbonate  be  dissolved  in  the  water  with  which  the 
guncotton  is  originally  saturated  for  the  purpose  of  obtaining 
it  in  this  non-explosive  form,  the  material,  whenever  it  is 
dried  for  conversion  into  cartridges,  or  employment  in  other 
ways,  will  contain  the  alkaline  matter  required  for  its  safe 
storage  and  use  in  the  dry  condition  in  all  climates.  Cold 
has  no  effect  upon  dry  guncotton,  but  of  course  if  low 
enough  it  may  freeze  the  water  in  the  wet  guncotton,  and 
when  the  latter  is  in  the  form  of  compressed  pulp,  as  now 


226  LECTURES   ON  EXPLOSIVES. 

issued,  the  freezing  will  cause  flaking,  cracking,  and  breaking 
down  of  the  physical  structure,  with  a  consequent  reduction  in 
density ;  hence  freezing  is  to  be  avoided  if  possible.  Alter- 
nate changes  from  heat  to  cold  and  the  reverse,  unless  exces- 
sive, have  little  effect  on  the  physical  structure  and  none  on 
the  chemical  stability  of  guncotton. 

Explosive  Effect  of  Guncotton. — From  what  has  been 
said  with  respect  to  the  products  of  explosion  of  gunpowder, 
it  might  be  expected  that  those  furnished  by  guncotton  would 
vary  according  to  the  conditions  under  which  the  explosion 
takes  place.  When  a  mass  of  the  guncotton  wool  is  ex- 
ploded in  an  unconfined  state  the  explosion  is  comparatively 
slow  (though  appearing  to  the  eye  almost  instantaneous),  since 
each  particle  is  fired  by  the  flame  of  that  immediately  adjoin- 
ing it,  the  heated  gas  (or  flame)  escaping  outwards,  so  that 
some  time  elapses  before  the  interior  of  the  mass  is  ignited. 
But  when  the  guncotton  is  inclosed  in  a  strong  case,  so  that 
the  flame  from  the  portion  first  ignited  is  unable  to  escape 
outwards  and  must  spread  into  the  interior  of  the  mass,  this 
is  ignited  simultaneously  at  a  great  number  of  points,  and 
the  decomposition  takes  place  far  more  rapidly ;  a  given 
weight  of  guncotton  being  thus  consumed  in  a  much  shorter 
time,  a  far  higher  temperature  is  produced,  and  the  ultimate 
results  of  the  explosion  are  much  less  complex,  as  would  be 
expected  from  the  well-known  simplifying  effect  of  high  tem- 
peratures on  chemical  compounds. 

Although  the  products  of  combustion  of  guncotton  have 
been  made  the  object  of  special  study  and  investigation,  the 
results  have  varied  between  wide  limits,  due  to  the  fact  that 
the  exact  composition  of  the  explosive  used  in  the  experi- 
ments has  almost  invariably  been  more  or  less  a  matter  of 
conjecture.  The  volume  of  permanent  gases  evolved  by  the 
explosion  of  one  gramme  of  guncotton  has  thus  varied  from 
483  c.c.  (Teschenmacher  and  Porret)  to  829  c.c.  (Karolyi), 
both  volumes  being  reduced  to  o°  C.  and  760  mm. 

The   composition  of  the  permanent  gases,  when  the  de- 


NITRIC  DERIVATIVE   EXPLOSIVE   COMPOUNDS.       22  7 


composition  of  the  explosive  occurred  in  vacua,  was  found  to 
be  as  follows : 


Hecker 
and  Schmidt. 

Teschenmacher 
and  Porret. 

Karolyi. 

Berthelot. 

*37.Ql£ 

IQ.O2# 

28.  55* 

41    Q# 

"         acid  ...         .... 

I  -i    02 

7  61 

IQ    I  I 

1  8  40 

Marsh-gas  

II  .  17 

I    ^O 

4-  ^6 

Cyanide     •              •  •  

37Q 

JC  .  -3C 

18  08 

8  8^ 

24    7O 

4.O^ 

1.82 

8  q6 

«;  80 

24.76 

47.66 

21  .en 

Hydrogen..    .......... 

700 

.yu 

ICO  .  OO 

100.00 

98.15 

IOO.OO 

The  determination  of  the  products  of  explosion  of  con- 
fined guncotton  was  effected  by  Karolyi  by  inclosing  the 
guncotton  in  a  cast-iron  cylinder  strong  enough  to  resist 
bursting,  until  the  combustion  of  the  last  portion  of  the 
charge  (which  was  suspended  in  an  iron  globe  exhausted  of 
air,  and  exploded  by  a  galvanic  battery)  was  complete;  the 
total  volume  of  the  resulting  gases  was  then  measured  and 
subjected  to  analysis. 

Unfortunately,  the  cellulose  nitrate  used  by  Karolyi  was 
not  pure  guncotton,  so  his  results  are  but  roughly  approxi- 
mate; still  they  indicate  that  the  reaction  might  proceed 
according  to  the  following  equation: 

2(C.H,0,)0,(NOO,  =  9CO  +  3CO,  +  7H,O  +  3N,, 

although,  naturally,  no  single  equation  would  be  likely  to 
represent  the  complex  reactions  involved  in  an  explosion  by 
ignition.  From  this  equation  we  deduce  that  one  gramme 
of  guncotton  yields  829  c.c.  of  gas  at  o°  and  76  cm.,  or,  with 
one  cubic  centimetre  of  compressed  guncotton  having  a  den- 
sity of  unity,  one  volume  of  this  guncotton  would  yield  829 
volumes  of  gas. 

From  his   experiments    Karolyi   found  that  the   state   of 


228  LECTURES   ON  EXPLOSIVES. 

the  gases  depends  upon  the  pressure  and  temperature  of  the 
explosion.  He  accounted  for  the  absence  of  nitric  oxide 
when  the  explosion  or  decomposition  occurred  under  high 
pressure  upon  the  assumption  that  at  increased  tempera- 
tures hydrogen  and  marsh-gas  acted  as  reducing  agents,  and, 
taking  oxygen  from  the  nitric  oxide,  contributed  to  the  for- 
mation of  COa ,  CO,  and  H2O,  with  the  liberation  of  free  N. 

As  the  result  of  their  investigations,  Sarrau  and  Vieille 
have  determined  the  total  heat  of  combustion  to  be  for  1 143 
grammes  of  explosive  633  cal. 

The  heat  of  formation  from  its  elements  would  be  624 
cal.  for  the  same  quantity  of  explosive  (Berthelot). 

Roux  and  Sarrau  have  determined  the  temperature  of  the 
gaseous  products  of  guncotton  at  the  moment  of  explosion  to 
be  3700°  C.,  while  the  experiments  of  Nobel  and  Abel  indi- 
cate the  maximum  temperature  to  be  4400°  C. 

In  their  investigations  Sarrau  and  Vieille  found  that  at 
high  pressure  the  aqueous  vapor  was  dissociated  and  more 
carbonic  acid  formed. 

Accepting  Vieille's  formula  for  the  composition  of  gun- 
cotton,  this  may  be  represented  by  the  equation 

2CMH,0,.(NO,)1,  =  24CO,+  24CO  +  i2H,0  +  i7H,+  i  iN, , 

and  by  calculation  we  find  that  the  initial  pressure  exerted  by 
guncotton  is  over  three  times  that  of  gunpowder,  and  that, 
like  that  of  gunpowder,  the  effect  is  reduced  in  practice  by 
the  incomplete  state  of  combination  of  the  elements  and  the 
complexity  of  the  products  which  they  tend  to  form,  and  the 
result  is  that  the  impact  becomes  less  brusque  and  more 
regular  as  the  combination  becomes  more  complete  during 
cooling. 

From  the  data  already  given  the  explosive  force  of  gun- 
cotton  may  be  readily  calculated.  Berthelot  estimates  the 
pressure  developed  by  the  detonation  of  guncotton,  of  den- 
sity i.i  under  constant  volume,  to  be  24,000  atmospheres, 
or  about  160  tons  per  square  inch. 


NITRIC  DERIVATIVE   EXPLOSIVE    COMPOUNDS.       22Q. 

Sebert  finds  the  rate  of  propagation  of  the  detonation, 
when  the  guncotton  is  confined  in  tubes  of  tin,  to  be  from 
5000  to  6000  metres  per  second,  while  it  is  but  4000  in  tubes 
of  lead.  Piobert  found  the  rate  of  inflammation  in  flocculent 
guncotton  in  free  air  to  be  eight  times  that  of  gunpowder. 

The  value  of  guncotton  as  a  military  explosive  was  much 
enhanced  by  the  discovery,  made  in  1868  by  E.  O.  Brown, 
of  the  Chemical  Department  at  Woolwich,  that  it  could  be 
detonated,  even  when  unconfined,  by  means  of  a  small  charge 
of  mercury  fulminate,  and  that  it  could  even  be  so  detonated 
when  thoroughly  saturated  with  water  if  only  a  small  initial 
charge  of  dry  guncotton  be  detonated  in  contact  with  it ;  and 
this  is  the  method  which  is  now  universally  used  for  produc- 
ing the  explosion  of  compressed  guncotton,  for  not  only  is 
it  easy  of  application  and  enables  us  to  explode  guncotton 
when  wet,  but  causes  the  explosive  to  develop  the  maximum 
force  in  a  very  small  interval  of  time,  and  thus  to  produce 
that  crushing  effect  which  is  desirable  in  a  torpedo  explosive. 

The  results  of  experiment  show  that  thoroughly  dry  gun- 
cotton  may  be  detonated  by  three  grains  of  mercury  fulmi- 
nate, and  air-dried  guncotton  by  five  grains,  provided  the 
fulminate  is  well  confined  in  copper  cases,  and  the  cases  are 
in  intimate  contact  with  the  guncotton. 

These  conditions  are  important  to  success.  Notwithstand- 
ing so  small  a  quantity  can  effect  the  detonation,  thirty-five 
grains  of  the  fulminate  are  used  in  the  U.  S.  Navy  detonators 
which  are  used  with  the  naval  torpedo  system. 

When  guncotton  or  any  other  high  explosive  is  tamped, 
we  obtain  a  more  violent  disruptive  effect  through  its  detona- 
tion than  when  it  is  untamped,  for  confinement  brings  about 
the  most  complete  decomposition.  When  freely  exposed  to 
the  air,  guncotton  is  supposed  to  be  untamped;  but  this  is  not 
strictly  true  with  this  or  any  other  high  explosive,  for  it  acts 
so  quickly  as  to  violently  disturb  and  set  in  motion  a  very 
considerable  mass  of  the  atmosphere,  and  this  atmosphere  acts 
as  a  tamp. 

Wet  guncotton  appears  to  be  a  more  violent  disruptive 


23O  LECTURES   ON  EXPLOSIVES. 

agent  when  detonated  than  dry  guncotton,  and  this  notwith- 
standing that  its  combustion  is  not  so  complete.  This  fact 
has  been  explained  by  supposing  that  the  water  in  its  pores, 
being  nearly  incompressible  and  highly  elastic,  increases  the 
rate  of  propagation  of  the  explosive  reaction,  and  hence  di- 
minishes the  time  factor. 

Soluble  Guncotton,  or  Collodion-cotton. — In  the  manufac- 
ture of  military  guncotton  various  other  forms  of  nitrocellu- 
lose are  formed,  .which  on  account  of  their  ready  solubility  in 
the  ether-alcohol  mixture,  as  well  as  in  other  solvents,  are 
known  under  the  generic  term  of  soluble  guncotton,  or  collo- 
dion-cotton. In  addition  to  existing  as  by-products  in  the 
manufacture  of  the  military  explosive,  soluble  guncotton,  on 
account  of  its  importance  in  several  industries,  is  manufactured 
very  extensively  on  a  commercial  scale.  The  principle  in- 
volved in  the  process  of  manufacture  is  identical  with  that 
already  stated  in  the  case  of  the  more  highly  nitrated  product. 

According  to  Eder's  formulae,  there  are  four  varieties  of 
soluble  guncotton,  viz.,  di-nitro-,  tri-nitro-,  tetra-nitro-,  and 
penta-nitrocellulose,  any  one  of  which  may  be  obtained  by 
varying  the  strength  of  the  acids,  the  temperature  of  the  acid 
mixture,  or  the  period  of  nitration. 

The  acid  mixture  most  generally  adopted  is  as  follows: 

HNO3  (sp.  gr.    1.44) I  part 

H2S04  (sp.   gr,    1.84) I     " 

During  the  process  of  nitration,  which  lasts  from  one-half  to 
one  and  one-half  hours,  the  temperature  of  the  acid  mixture 
is  kept  at  about  40°  C.  In  every  other  respect  the  process 
of  conversion,  extraction,  washing,  etc.,  is  identical  with  that 
to  be  described  in  the  following  lecture. 

Nitro-hydrocellulose. — By  treating  cellulose  with  dilute 
sulphuric  or  hydrochloric  acid,  it  absorbs  water  and  is  reduced 
to  a  very  fine  powder,  in  which  form  it  is  very  readily  nitrated. 
The  resulting  powder  is  called  hydrocellulose  (Aime  Girard), 
and  the  nitrated  product  obtained  by  treating  it  with  nitric 
acid  is  known  as  nitro-hydrocellulose.  The  usual  method  of 


NITRIC  DERIVATIVE  EXPLOSIVE    COMPOUNDS.       23! 

manufacture  is  to  steep  the  carefully  prepared  cotton  for  a 
few  minutes  in  an  acid  mixture  consisting  of 

HSSO4  (sp.  gr.  1.84) 3  parts 

H30 97       " 

or 

HC1  (sp.  gr.  1.20) 3        " 

H20 97       « 

It  is  then  freed  from  acid  and  dried,  and  as  soon  as  dry  it 
readily  breaks  up  and  forms  a  pulverulent  mass.  By  using 
stronger  acids  and  immersing  the  cotton  for  twelve  hours,  the 
conversion  into  hydrocellulose  proceeds  quietly,  and  forms 
into  a  compact  body  at  the  bottom  of  the  trough  or  jar,  from 
which  the  supernatant  acid  mixture  may  be  separated  by 
decantation,  and  the  mass  washed  and  rewashed  in  the  same 
vessel  until  entirely  free  from  acid.  When  dry  the  cake  is 
easily  reduced  to  powder  by  sieving  or  other  means. 

The  subsequent  process  of  nitrating  the  hydrocellulose  is 
similar  in  every  respect  to  that  to  be  described  in  the  case  of 
guncotton,  with  the  exception  that  no  pulping  is  necessary, 
and  the  resulting  guncotton  is  very  uniform  and  of  a  very 
high  grade. 

Nitro-hydroc.ellulose  is  more  sensitive  to  shock  than 
ordinary  guncotton,  and  its  use  has  as  yet  been  limited  to  the 
manufacture  of  detonating  fuses  and  primers  for  blasting  gel- 
atine 

Nitrcstarch. — The  composition  of  starch  is  identical 
with  that  of  cellulose,  ?zC6H]0O6,  and  by  subjecting  it  to  the 
action  of  nitric  acid  analogous  nitric  derivatives  are  obtained. 
Thus,  assuming  n  to  be  unity,  since  its  exact  value  is  not  yet 
definitely  known,  the  equation  representing  the  reaction  may 
be  written  as  follows : 

C.H,0.(OH).  +  3HO,NO.  -  (C5H,O,)O,(NO,)8  +  3H,O, 

which  is  identical  with  that  representing  the  conversion  of 
cotton  into  guncotton.  By  varying  the  strength  of  the  nitric 


232  LECTURES   ON  EXPLOSIVES. 

acid,  and  modifying  other  conditions,  the  lower  grades, 
mono-nitro-  and  di-nitrostarch,  may  be  obtained.  For  me- 
chanical reasons  it  is  found  advisable  not  to  introduce  the 
starch  into  a  mixture  of  nitric  and  sulphuric  acids  as  in  the 
case  of  nitrating  cotton,  but  to  dissolve  the  starch  in  nitric  acid 
first,  and  then  introduce  the  solution,  when  cool,  into  the 
mixed  acids. 

Practically  the  following  proportions  have  been  found  to 
give  good  results : 

c  .     .       (Starch I  part 

Solution  \  TTAT^    ,  , 

(  HNO3  (sp.  gr.  1.50) 10  parts 

HNO,  (sp.  gr.  1. 06) i  part 


Acid  mixture  i  TT  ~.~    ,  ^   . 

H3SO4  (sp.  gr.  1.62)  .......     2  parts 

Solution  .  .  ...............................      i  part 

Acid  mixture  ............................      5  parts 

Waste  acids  from  the  manufacture  of  nitroglycerine,  to 
which  about  2ofo  of  water  is  added,  may  be  used  for  the  acid 
mixture. 

The  starch  solution  is  introduced  into  the  mixed  acids  in 
a  finely  divided  state,  and  the  nitrostarch  forms  as  a  pul- 
verulent precipitate  at  the  bottom  of  the  vessel  containing 
the  acid  mixture,  whence  it  is  removed  and  thoroughly 
cleansed  from  all  traces  of  acidity. 

If,  as  in  the  case  of  cellulose,  we  assume  that  starch  is 
a  condensed  molecule,  the  formula  would  be  a  multiple  of 
C6H10O6,  and  upon  this  assumption  other  grades  of  nitro- 
starch are  possible.  Thus,  experimentally,  tetra-nitro-,  penta- 
nitro-,  and  hexa-nitrostarch  have  been  obtained,  having  the 
following  compositions  respectively  : 


H,  —  tetra-nitrostarch  with  11.11%  of  N 
(CiaHuO4)O6(NO2)6Ha  =  penta-nitrostarch  "  12.75  "  " 
(ClaH14O4)O6(NO2)flH  =  hexa-nitrostarch  "  14.14  "  " 

Rather    curiously,    nitrostarch   precipitated    by  water    or 


NITRIC  DERIVATIVE  EXPLOSIVE    COMPOUNDS.       233 

weak  sulphuric  acid  appears  to  be  more  stable  than  similar 
compounds  prepared  by  using  the  concentrated  acid. 

Nitrostarch  seems  rather  liable  to  undergo  ''spontaneous 
decomposition,"  and  as  yet  it  has  not  been  used  to  any  con- 
siderable extent  in  the  manufacture  of  explosives.  It  is  very 
hygroscopic,  insoluble  in  water  and  alcohol,  but  dissolves 
readily  in  a  mixture  of  ether  and  alcohol,  and  in  acetic  ether, 
and  also  in  nitroglycerine.  The  ignition-point  of  nitrostarch 
varies  from  155°  C.  to  175°  C.,  according  to  its  composition. 

Having  almost  the  same  chemical  composition  as  cellulose, 
the  glucoses  and  saccharoses  have  been  experimented  with  as 
substances  capable  of  nitration  with  the  possible  production 
of  nitro-explosives.  Thus,  nitroglucose,  nitrosaccharose, 
nitrolactose,  and  nitromannite  (the  latter  derived  from  the 
hexatomic  alcohol,  mannite  or  mannitol)  have  been  obtained, 
but  as  yet  none  of  these  products  have  proven  of  practical 
value. 


LECTURE    XII. 

MANUFACTURE    OF    GUNCOTTON    AT    THE    U.    S.    NAVAL 
TORPEDO    STATION. 

THE  cotton  used  at  this  station  is  the  kind  known  as 
"  weaver's"  or  "cop"  waste.  It  is  the  tangled  clippings 
from  the  spinning-room,  and  is  received  in  bales  containing 
about  500  pounds  each.  This  form  of  cotton  is  preferred  to- 
cotton  "wool"  on  the  ground  that  the  thready  form  pre- 
vents the  material  from  packing  closely  together  when  wet  by 
the  alkaline  solutions,  water,  or  acids  used  in  the  various  proc- 
esses through  which  it  is  passed,  and  thus  permits  of  more 
complete,  uniform,  and  speedy  treatment,  while  it  diminishes 
the  chances  of  fuming  during  "dipping."  Besides  the  orig- 
inal cost  of  the  waste  is  less  than  that  of  cotton  of  a  market- 
able length.  The  waste  as  received  contains  knots,  "  cops  " 
(small  bits  of  paper  upon  which  the  thread  is  wound),  dirt 
and  oil  from  the  machines,  together  with  incrusting  sub- 
stances naturally  existing  on  the  fibres,  and  hygroscopic 
moisture  all  of  which  must  be  removed  before  the  material 
is  subjected  to  the  nitrating  process.  Hence  the  first  step  is 
the  manual  sorting  of  the  waste  to  remove  the  larger  foreign 
bodies,  such  as  nails,  pebbles,  bits  of  wood,  metal,  and  paper, 
which  are  sometimes  found  in  it,  and  then  the  waste  passes 
to  the 

First  Boiling-tub. — This  is  a  covered  tub  which  is  heated 
by  live  steam.  The  tub  is  made  of  white  pine  and  has  a 
capacity  of  500  gallons.  Two  hundred  (200)  pounds  of  cotton 
are  placed  in  the  tub,  to  which  250  gallons  of  water  and  35, 

234 


MANUFACTURE    OF  GUNCOTTON.  2$$ 

pounds  of  caustic  soda  are  added,  the  steam  is  turned  on,  and 
the  whole  maintained  at  the  boiling-point  for  eight  hours. 
The  liquid  is  then  drained  off  from  the  cotton,  which  remains 
thus  overnight,  when  the  tub  is  filled  with  clear  water  and 
the  boiling  continued  for  eight  hours  more  and  again  drained 
overnight.  By  the  manual  picking  the  larger  masses  of  for- 
eign bodies  have  been  removed.  By  the  boiling  with  alkali 
the  oils  are  saponified,  and  the  soap  formed  acts  as  a  deter- 
gent and  removes  much  of  the  dirt,  while  the  boiling  alkaline 
solution  acts  also  as  a  solvent  for  the  incrusting  matter.  This 
process  affects  the  fibre,  for  by  prolonging  the  boiling  with 
the  alkaline  solution  or  increasing  the  amount  of  alkali  the 
fibre  is  materially  weakened,  and  advantage  may  be  taken  of 
this  to  facilitate  the  operation  of  pulping,  but  the  gain  in  this 
direction  does  not  compensate  for  the  loss  in  the  product, 
while  the  hot,  strong  alkali  solution  rapidly  destroys  the  tub. 
From  the  first  boiling-tub  the  wet  cotton  passes  to  the 
First  Centrifugal  Washer. — This  is  a  machine  of  the 
ordinary  form  and  construction,  being  26  inches  in  diameter, 
J-inch  mesh,  and  making  about  1400  revolutions  per  minute. 
From  6  to  7  pounds  of  the  cotton  are  put  in  the  centrifugal 
at  a  charge,  the  wringer  is  set  in  revolution,  and  a  stream  of 
fresh  water  is  turned  on  the  cotton  and  allowed  to  play  upon 
it  until  the  slippery  feeling  (due  to  the  alkali)  has  disappeared. 
This  operation  requires  about  eight  minutes,  and  the  washing 
of  the  whole  charge  from  the  boiling-tub  requires  two  hours. 
From  here  the  cotton  passes  to  the 

First  Drying-room. — This  is  a  room  5  feet  10  inches 
by  1 1  feet  4  inches  and  1 1  feet  high,  the  walls  and  ceilings 
of  which  are  sheathed  with  asbestos  paper.  Around  two  sides 
of  this  room  are  nine  rows  of  shelves  or  racks  made  of  galvan- 
ized iron  wire  netting  I-  to  -J-inch  mesh.  Hot  air  enters  the 
room  from  the  final  drier  through  a  flue  in  one  side  and  near 
the  floor,  which,  after  passing  about  and  through  the  cotton 
on  the  shelves,  issues  by  a  ventilating  flue  at  the  top  of  the 
room.  By  the  aid  of  the  hot  air  the  temperature  of  this  dry- 
ing-room is  maintained  at  about  187°  F. 


236  LECTURES   ON  EXPLOSIVES. 

The  cotton  from  the  wringer  is  spread  on  the  shelves  in  a 
layer  about  2  to  4  inches  thick,  and  it  remains  in  this  room, 
being  turned  every  day,  after  the  second  day,  until  it  is  per- 
fectly dry  to  the  touch.  The  time  for  drying  varies  from 
three  to  five  days. 

From  the  drying-room  the  cotton  passes  to  the 

Picker. — This  is  the  ordinary  machine  used  in  cotton- 
mills,  and  consists  of  an  endless  flexible  table  upon  which  the 
cotton  is  fed,  two  small  horizontal  cylinders,  armed  with 
teeth,  rotating  in  opposite  directions,  and  a  large  wooden 
drum  which  is  also  armed  with  teeth.  As  has  been  said,  the 
cotton  waste  as  received  is  badly  tangled  and  contains  many 
knots  and  rolls.  It  can  be  readily  understood  that  the  stir- 
ring and  boiling,  produced  by  the  live  steam  in  the  boiling- 
tub,  tends  to  tangle  the  mass  still  more.  The  complete  con- 
version of  the  cellulose  depends  to  a  large  degree  upon  the 
form  of  the  cotton  when  it  goes  into  the  acid.  If  knots  and 
rolls  be  present  in  the  cotton  they  produce  more  or  less  "  fir- 
ing," and  they  are  more  or  less  yellow  after  the  conversion. 
The  picker  serves  to  straighten  out  the  tangled  mass  and 
open  up  the  knots  and  rolls,  so  that  the  acid  may  have  ready 
access  to  the  fibre,  but  the  cylinders  of  the  picker  should  be 
so  adjusted  that  the  thread  is  not  torn  apart  by  this  process. 
It  takes  about  two  hours  to  pass  200  pounds  of  cotton 
through  the  picker,  and  it  results  in  about  3  pounds  of  loss. 
The  cotton  passes  from  the  picker  to  the 

Final  Drying-closet. — This  consists  of  a  large  closet  6 
feet  *J\  inches  long,  4  feet  wide,  and  5  feet  4^  inches  high, 
made  of  galvanized  iron,  which  contains  two  sets  of  six 
drawers,  each  2  feet  wide,  3  feet  10  inches  long,  and  4  inches 
deep,  made  of  the  same  material,  with  the  exception  of  the 
bottoms,  which  are  made  of  galvanized  iron  wire  netting  of  \- 
to  I -inch  mesh.  These  drawers  are  5  inches  apart  vertically 
with  a  sheet  of  J-inch  galvanized  iron  between  them  which 
serves  to  deflect  the  current  of  heated  air.  Air  which  has 
been  drawn  over  a  steam  radiator  is  driven  into  this  closet 
by  means  of  a  No.  4  Sturtevant  blower,  and  led  about  and 


MANUFACTURE   OF  GUNCOTTON.  237 

through  the  cotton  out  of  the  drying-room.  By  means  of 
this  hot  air  the  temperature  of  the  closet  is  maintained  at 
about  225°  F.,  but  has  varied  from  200°  to  260°  F.  The 
cotton  from  the  picker,  which  contains  from  6  to  10  per  cent 
of  moisture,  as  all  atmospherically  dry  cotton  does,  is  spread 
over  the  drawers  in  a  layer  about  4  inches  thick,  and  the 
drawers  are  then  closed.  The  cotton  is  allowed  to  remain  in 
the  drying-closet  for  eight  hours,  at  the  end  of  which  time 
it  is  estimated  to  contain  from  .25  to  .50  percent  of  mois- 
ture. One  half  of  one  per  cent  is  the  largest  amount  of  mois- 
ture which  the  cotton  may  contain  at  the  time  of  dipping.  With 
a  large  amount,  even  if  it  only  reaches  to  one  per  cent,  a  re- 
action takes  place  by  which  unstable  compounds  are  formed 
which  are  not  removed  by  the  subsequent  treatment  which 
the  guncotton  undergoes.  It  is  stated  that  an  amount  of 
moisture  which  is  seriously  objectionable  when  present  in 
the  cotton  at  the  time  of  dipping  it  in  the  acids  may  be 
present  in  the  acids  in  which  the  cotton  is  dipped  without 
material  harm  to  the  process  or  product.  In  order  that  the 
highest  nitric  ester  may  be  obtained,  it  is  essential  that  the 
cotton  at  the  time  of  dipping  should  be  pure,  dry,  and  cool. 
Hence,  in  order  to  cool  it  out  of  contact  with  the  air,  it  is 
packed  directly  from  the  drawers  of  the  final  drying-closet, 
and  while  yet  hot  into  service  powder-tanks,  the  covers  of 
which  are  screwed  on  air-tight,  and  then  the  whole  is  allowed 
to  stand  in  a  cool  room  overnight.  The  i5O-pound  powder- 
tank  holds  about  ten  pounds  of  cotton  when  filled  by  hand- 
pressure.  The  tanks  containing  the  cool  cotton  are  then 
transported  by  tram-cars  running  through  the  factory  to  the 

Dipping-  or  Converting-room. — This  room  contains  the 
dipping-troughs,  acid-reservoirs,  digestion-pots,  and  cooling- 
troughs. 

Dipping-troughs. — Five  of  these,  each  having  a  capacity 
for  about  150  pounds  of  mixed  acids,  are  used.  They  are 
made  of  cast  iron,  and  are  set  in  an  iron  trough  in  which  cold 
water  circulates,  which  serves  to  keep  the  acid  below  70°  F. 
during  the  process  of  conversion.  At  the  rear  and  top  of 


238  LECTURES   ON  EXPLOSIVES. 

each  trough  is  an  iron  shelf  or  grating,  upon  which  the  par- 
tially converted  cotton  is  squeezed,  and  above  this  is  an  iron 
rod  to  which  a  hook  in  the  end  of  the  lever-press  is  attached 
during  the  process  of  squeezing.  Only  four  of  the  troughs 
are  used  for  dipping  the  cotton  in,  the  first  being  used  as  a 
reservoir  for  acid  for  immediate  consumption.  The  troughs 
are  placed  side  by  side  under  a  wooden  hood,  and  a  flue  in 
the  rear  of  this  hood  leads  the  acid  fumes  evolved  into  a 
vacuum-chamber  at  the  rear  which  connects  with  the  suction- 
pipe  of  the  ventilating-fan  that  ejects  the  fumes  through  a 
flue  in  the  roof  of  the  factory. 

Acids. — The  acids  employed  in  the  manufacture  are  pur- 
chased according  to  the  following  specifications : 

The  mixed  acid  to  consist  of  one  part  by  weight  of  nitric 
acid  to  three  parts  by  weight  of  sulphuric  acid.  The  nitric 
acid  must  have  a  real  specific  gravity  of  1.5,  at  a  temperature 
of  15°  C.,  and  be  free  from  chlorine  and  its  compounds.  The 
color  must  not  be  darker  than  straw.  The  acid  must  not 
contain  sulphuric  acid  in  sufficient  quantities  to  perceptibly 
raise  the  specific  gravity.  The  sulphuric  acid  must  have  a 
real  specific  gravity  of  not  .less  than  1.845,  and  be  clear  and 
colorless.  The  acids  are  delivered  in  wrought- iron  cylin- 
drical drums  3  feet  3  inches  long,  28  inches  in  diameter,  and 
I  inch  thick,  and  each  holding  about  1200  pounds  of  mixed 
acids.  With  the  present  knowledge  of  mixed  acids  there  is 
no  certain  method  of  inspection  except  by  the  chemist  from 
the  station  making  an  examination  of  the  separate  acids  at 
the  acid  works  before  the  acids  are  mixed,  and  then  super- 
vising the  mixing.  By  thoroughly  studying  the  question 
means  will  undoubtedly  be  discovered  for  determining  whether 
or  not  the  mixed  acids  conform  to  the  specifications,  but  this 
has  not  yet  been  accomplished.  A  preliminary  investigation 
has,  however,  shown  that  the  specific  gravity  of  the  mixed 
acids  is  not  the  mean  specific  gravity  of  the  components,  and 
that  a  contraction  in  volume  has  taken  place.  The  examina- 
tion is  complicated  by  the  fact  that  the  acid  as  received  con- 
tains a  white,  finely  divided  solid  in  suspension  which  does 


MANUFACTURE    OF  GUNCOTJON.  239 

not  settle  completely  until  standing  for  two  weeks  or  more. 
To  remove  it  by  filtration  is  in  the  nature  of  things  a  difficult 
operation.  This  suspended  solid  appears  to  be  a  basic  sul- 
phate of  iron  resulting  from  the  slight  action  of  the  acids  on 
the  metal  of  the  drums.  Notwithstanding  this  action  these 
drums  offer  the  cheapest,  safest,  and  altogether  the  most 
practical  means  of  transporting  the  acids.  Before  their  use 
the  separate  acids  were  transported  to  the  station  in  glass  or 
acid-proof  stoneware  carboys  and  mixed  when  desired  for 
use.  While  this  method  gave  a  better  check  on  the  quality 
of  acid  delivered,  the  serious  fires  and  accidents  which  re- 
sulted from  breakage  during  transportation  led  to  its  aban- 
donment. The  acid  from  the  drums  is  pumped  into  large 
acid-proof  stoneware  reservoirs  in  the  dipping-room,  and  from 
there  it  is  led  by  a  conductor  into  the  dipping-troughs. 

Dipping  the  Cotton. — The  cotton  is  weighed  out  in  one- 
pound  lots.  Each  lot  is  then  divided  into  three  nearly  equal 
parts,  which  are  successively  and  rapidly  worked  into  the  acids 
in  the  dipping-trough  by  means  of  the  steel  fork,  the  separate 
portions  being  well  stirred  about  in  the  acid  to  prevent  any 
local  rise  in  temperature.  When  the  whole  is  immersed  a  10- 
minute  sand-glass  is  turned  and  the  "  dipper  "  passes  on  to  the 
next  trough,  where  this  operation  is  repeated.  By  the  time 
he  has  filled  the  fourth  trough  with  its  charge  the  sand  has 
run  its  course  above  the  first  trough,  so  this  charge  is  with- 
drawn from  the  acid,  placed  upon  the  grating,  squeezed  by 
the  lever-press  as  completely  as  possible  and  then  placed  in 
the  digestion-pot. 

The  Lever-press  is  an  iron  bar  about  5  feet  long,  having 
a  hook  at  one  end.  A  plate  is  attached  to  the  bar  by  a  pivot 
about  8  inches  from  the  hook.  To  use  the  press  the  hook  is 
attached  to  the  rod  above  the  dipping-trough,  the  plate  is 
placed  on  the  cotton,  and  pressure  is  applied  to  the  longer  end 
of  the  lever. 

Digestion-pot. — This  is  an  ordinary  two-gallon  crock 
made  of  coarse  stoneware,  glazed  inside  and  out,  and  pro- 
vided with  a  cover.  It  is  of  the  first  importance  that  the 


240  LECTURES   ON  EXPLOSIVES. 

pot  should  be  sound  and  the  glaze  intact  so  that  no  leaking 
can  take  place,  for  if  moisture  should  reach  the  charge  in  the 
crock  the  latter  would  be  "fired."  Immediately  before  use 
the  pots  are  wiped  out  with  a  little  acid  so  as  to  remove  any 
moisture  which  may  have  accumulated  or  condensed  on  their 
walls.  This  process  is  technically  known  as  "  drying-out." 
The  mass  of  partially  converted  cotton  saturated  with  acid 
weighs,  as  placed  in  the  pot,  from  10  to  12  pounds.  When 
it  is  put  in  the  pot  it  is  squeezed  down  compactly  by  means 
of  a  hand-press,  and  the  pot  is  then  covered  and  placed  in 
water  in  the  cooling-trough,  where  it  remains  overnight.  A 
gang  of  two  men  can  thus  treat  100  pounds  of  cotton  in  a 
working  day  of  8  hours. 

Cooling-troughs.  —  These  are  made  of  wood  2  inches 
thick,  are  rectangular  in  shape,  are  lined  with  lead  and  pro- 
vided with  a  water-tap  at  one  end  and  an  overflow-pipe  at 
the  other.  The  latter  pipe  is  just  high  enough  and  of  such 
size  as  to  prevent  the  water  in  the  trough  from  rising  above 
the  level  of  the  acid  and  guncotton  in  the  pots.  The 
troughs  are  I  foot  5  inches  wide,  8^  inches  deep,  and  24  feet 
6  inches  long.  Each  one  will  hold  20  pots.  Six  are  used, 
and  one  is  reserved  for  emergencies.  Cold  water  is  kept  cir- 
culating through  these  troughs  in  summer,  but  in  winter  they 
are  simply  filled  with  water.  From  the  cooling-troughs  the 
guncotton  passes  to  the 

Acid-wringer. — This  is  a  centrifugal  wringer  made  of 
mild  steel  and  provided  with  a  cover  to  prevent  the  acid  or 
acid  fumes  from  escaping.  The  wringer  is  20  inches  in 
diameter  and  9  inches  deep,  has  a  -J-inch  mesh,  and  makes 
1400  revolutions  per  minute.  It  is  provided  with  a  flue 
leading  to  a  ventilating-fan  by  which  the  fumes  are  driven 
into  the  outer  atmosphere,  while  a  pipe  from  the  bottom 
leads  the  extracted  acid  in  a  receiver  in  the  factory  cellar. 
Before  using  for  the  day  this  wringer  is  "dried  out"  by 
pouring  in  a  pitcherful  of  acid  and  rotating  the  basket.  Two 
pots  full  of  guncotton  are  wrung  at  one  operation,  and  this 
occupies  from  three  to  four  minutes.  The  operation  should 


MANUFACTURE   OF  GUNCOTTON.  241 

be  conducted  with  caution,  and  extreme  care  should  be  taken 
that  no  moisture  or  oil  reaches  the  mass.  As  the  digestion- 
pots  have  been  immersed  in  water  in  the  cooling-troughs,  it 
is  necessary  to  let  them  drain  and  to  dry  their  outer  surface 
before  taking  them  to  the  acid-wringer.  Several  explosions 
or  "firings"  which  have  taken  place  in  wringers  have  been 
traced  to  drops  of  oil  from  the  machinery,  or  of  perspiration 
from  the  faces  of  the  workmen,  which  have  fallen  on  the  gun- 
cotton.  The  wrung  guncotton  is  taken  from  the  wringer  by 
hand,  the  hands  being  covered  with  rubber  gloves,  and  it 
then  passes  to  the 

Immersion-tub.  —  This  is  a  wooden  tub  of  800  gallons 
capacity,  provided  with  a  perforated  false  bottom,  and  hav- 
ing a  3^-inch  inlet  and  a  3^-inch  outflow-pipe.  At  one  end  is 
a  wooden  drum  2  feet  in  diameter,  provided  with  feathers,  and 
placed  so  as  to  be  nearly  one-half  immersed  in  the  water  of 
the  tub  when  the  tub  is  filled.  This  cylinder  rotates  hori 
zontally  about  its  axis,  and  serves  as  a  beater  to  carry  the 
guncotton  under  the  water.  Above  the  tub  and  at  one  side 
of  the  beater  is  placed  a  wooden  box  or  hopper,  lined  with 
lead,  which  is  provided  with  a  door  in  the  side,  through 
which  the  guncotton  is  introduced  into  the  hopper,  and  a 
slot  in  the  bottom  by  which  the  guncotton  is  fed  to  the  tub. 
The  object  of  the  immersion  process  is  to  wash  out  the 
greater  portion  of  acid  from  the  guncotton.  As  stated 
above,  a  small  quantity  of  water  is  likely  to  cause  "  firing"; 
hence,  to  effect  this  washing  successfully,  it  is  necessary  to 
use  very  small  portions  of  guncotton  at  a  time,  to  use  very 
large  quantities  of  water  so  as  to  drown  the  guncotton,  and 
to  perform  the  operation  so  quickly  that  the  acid  is  removed 
from  the  guncotton  and  distributed  through  the  great  body 
of  water  before  any  local  heating  can  take  place.  This  is 
effected  as  follows:  The  tub  being  filled  with  water,  the 
water  flowing  at  full  speed,  and  the  beater  being  in  rotation, 
two  crocks  of  wrung  guncotton  are  placed  in  the  hopper. 
Then  the  workman  inserts  his  hand,  protected  by  a  rubber 
glove,  and  little  by  little  pushes  the  guncotton  through  the 


242  LECTURES   ON  EXPLOSIVES. 

slot,  and  this  operation  is  repeated  until  fifty  crocks  are  fed 
into  the  tub.  When  well  washed  the  guncotton  is  placed 
in  a  wooden  rack  to  drain.  Owing  to  the  scarcity  of  fresh 
water  at  the  torpedo-station  salt  water  is  used  in  the  immer- 
sion-tub, so  the  guncotton  from  the  tub  is  wrung  out  in  a 
centrifugal  wringer,  and  washed  with  fresh  water  until  the 
salty  taste  has  disappeared.  Two  crockfuls  are  wrung  at  a 
time,  and  three  washings  are  generally  sufficient.  No  matter 
how  much  the  guncotton  is  washed  in  cold  water,  it  still 
retains  acids  or  easily  decomposed  material,  which  can  only  be 
removed  by  boiling;  hence  from  the  immersion-tub  the  gun- 
cotton  passes  to  the 

Second  or  Guncotton  Boiling-tub. — This  consists  of  a 
wooden  tub  of  300  gallons  capacity,  which  is  provided  with  a 
perforated  false  bottom  and  heated  by  a  steam-coil.  The 
inlet-pipe  and  coil  are  cut  off  from  the  interior  of  the  tub  so 
that  the  metal  cannot  come  in  contact  with  the  guncotton. 
Here  fifty  pots  of  guncotton  are  boiled  for  eight  hours  in 
fresh  water  to  which  10  pounds  of  carbonate  of  soda  have 
been  added,  then  drained  overnight,  washed  with  fresh  water 
in  a  centrifugal  wringer,  returned  to  the  boiling-tub,  boiled 
with  fresh  water  for  eight  hours,  again  drained  overnight  and 
again  washed  with  fresh  water  in  the  centrifugal.  The  gun- 
cotton  next  passes  to  the 

Pulper. — This  machine  is  the  ordinary  "beater,"  "rag- 
engine,"  or  Hollander,"  used  in  paper-mills,  and  consists  of  a 
wooden  tub  12  feet  long,  5  feet  wide,  and  2  feet  deep,  with 
curved  ends.  The  tub  is  partially  divided  along  its  longer 
axis  by  a  wooden  partition  (of  the  same  height  as  the  walls  of 
the  tub)  into  two  parts — the  "working  side,"  in  which  the 
guncotton  is  shredded  between  the  knife-edges  on  the  revolv- 
ing cylinder  and  those  on  the  "craw,"  and  the  "running 
side,"  into  which  the  shredded  material  is  thrown  by- the  re- 
volving cylinder.  The  revolving  cylinder  is  of  wood,  is  28 
inches  in  diameter,  28  inches  long,  carries  forty  crucible-steel 
knives,  and  rotates  two  hundred  times  a  minute.  Under  the 
cylinder  is  a  massive  oak  block,  called  the"  craw,"  the  concave 


MANUFACTURE   OF  GUNCOTTON.  243 

surface  of  which  equals  one  fourth  the  circumference  of  the 
cylinder.  The  side  of  the  block  leading  to  the  curved  face  is 
gently  inclined,  while  on  the  side  beyond  the  curved  face  it  is 
sharply  inclined.  In  the  centre  of  the  craw  below  the  revolv- 
ing cylinder  is  fitted  a  box  of  steel  knives,  and  the  cylinder  is 
so  adjusted  by  set-screws  attached  to  the  socket  in  which  its 
shaft  revolves  that  its  knives  just  clear  the  bundle  of  knives 
in  the  craw.  The  cylinder  is  enclosed  in  a  wooden  cover, 
extending  nearly  the  length  of  the  partition,  to  prevent  loss  of 
the  material  by  centrifugal  action.  From  300  to  350  pounds 
of  guncotton  are  slowly  fed  into  the  pulper,  and  water  is 
added  until,  when  the  cylinder  is  revolving,  the  mass  just 
reaches  the  top  of  the  tub  to  the  right  of  the  cylinder.  Dur- 
ing the  feeding  the  guncotton  is  held  in  a  wall-pocket  made 
of  thin  boards  and  canvas,  which  is  placed  at  the  left-hand 
end  of  the  pulper.  When  the  cylinder  is  set  in  revolution  the 
guncotton  is  drawn  between  the  knives  and  shredded  and  the 
paste  forced  over  the  craw,  where,  as  it  flows  sluggishly,  it  is 
heaped  higher  than  at  the  other  end  of  the  tub,  but  it  gener- 
ally flows  to  the  other  end,  is  drawn  again  between  the  knives, 
and  so  it  continues  until  the  whole  of  the  guncotton  is  cut  to 
the  fineness  of  corn  meal.  When  the  pulper  is  in  good  work- 
ing order  this  operation  takes  two  days  fora  charge  of  the 
size  stated  above.  The  mass  is  then  run  off  into  the 

Poacher. — This  is  a  wooden  tub  similar  in  form  to  the 
pulper,  but  the  cylinder  is  armed  with  wooden  feathers  instead 
of  knives,  and  it  serves  simply  to  keep  the  guncotton  in  sus- 
pension in  the  water  and  to  keep  the  whole  in  mass  in  rotation 
about  the  tub.  The  poacher  has  a  capacity  of  about  900  gal- 
lons. When  the  pulp  has  reached  the  poacher  the  guncotton 
is  allowed  to  settle,  and  the  water  is  drained  off  by  means  of 
a  telescopic  overflow-pipe  in  one  end  of  the  poacher.  The 
tub  is  filled  with  fresh  water,  the  cylinder  set  in  revolution, 
and  the  circulation  kept  up  for  one  hour,  when  the  settling 
and  draining  is  repeated,  and  these  operations  are  continued 
for  two  days,  making  about  six  washings  and  settlings,  when 
a  sample  is  drawn  and  tested.  If  the  sample  fails  to  pass  the 


244  LECTURES   ON  EXPLOSIVES. 

test  the  washing  in  the  poacher  is  continued  until  the  gun- 
cotton  will  pass.  When  thoroughly  washed  the  guncotton 
is  again  drained,  3  pounds  of  precipitated  chalk,  .3  pounds 
of  caustic  soda,  300  gallons  of  lime-water,  and  sufficient 
water  to  make  the  whole  up  to  about  800  gallons,  are  added 
to  it,  and  the  whole  is  sucked  up  by  means  of  a  vacuum-pump 
into  the 

Stuff-chest. — This  is  a  cylindrical  iron  vessel  of  about 
850  gallons  capacity,  fitted  with  a  manhole  at  the  top,  which 
is  closed  by  an  air-tight  cover,  and  provided  at  the  bottom 
with  an  inlet-pipe  through  which  the  pulp  enters,  and  an  out- 
let-pipe through  which  the  pulp  is  delivered.  Through  the 
centre  of  the  tank  is  a  vertical  shaft,  which  is  provided  with  four 
feathers,  and  which  is  geared  to  a  horizontal  shaft  above  it. 
The  object  of  this  stirrer  is  to  keep  the  guncotton  and  other 
solids  uniformly  suspended  in  the  liquid  so  that  the  same 
proportions  of  each,  as  nearly  as  possible,  may  be  delivered 
to  the  moulding-press.  The  stirrer  is  run  for  about  twenty 
minutes  before  the  moulding  begins,  and  is  kept  in  operation 
until  the  moulding  ceases.  The  stuff-chest  rests  upon  stringers 
at  the  top  of  the  factory  so  that  its  contents  may  gravitate  to 
the  press.  The  pulp  first  goes,  however,  to  the 

Wagon,  which  is  a  cylindrical  copper  vessel  of  about  25 
gallons  capacity,  suspended  by  rollers  upon  a  railway  so  that 
the  top  of  the  vessel  just  clears  the  outlet-pipe  of  the  stuff- 
chest,  while  the  bottom  is  well  clear  of  the  top  of  the  moulding- 
press.  Inside  the  wagon  is  a  vertical  stirrer,  similar  to  that 
in  the  stuff-chest  and  playing  the  same  part,  which  is  geared 
to  a  horizontal  shaft  that  rotates  between  the  rails.  The  pulp 
is  delivered  by  an  orifice  in  the  bottom,  which  is  closed  by  a 
valve  which  moves  vertically  and  is  operated  by  a  lever  and 
cord  at  the  top  of  the  wagon.  A  one-inch  rubber  tube  one 
foot  long  is  attached  to  the  outlet  of  the  wagon  so  as  to  assist 
in  delivering  the  pulp  at  the  desired  point.  The  wagon  is 
filled  by  rolling  it  under  the  stuff-chest  and  opening  the  valve 
in  the  outlet-pipe  of  the  latter.  The  stirrer  then  being  in  rota- 
tion, the  wagon  is  rolled  along  until  it  reaches  the  moulding- 


MANUFACTURE    OF  GUNCOTTON.  245 

press,  when  the  rubber  tube  is  led  successively  to  each  com- 
partment of  the  moulding-press,  the  lever  is  pulled,  and  the 
press  is  loaded.  One  wagon-load  serves  for  about  three 
charges  for  the  moulding-press. 

Moulding-press.  —  This  is  a  hydraulic  press  made  of 
bronze  and  containing  four  rectangular  compartments  2.8 
inches  square  with  chamfered  corners.  The  press  is  closed 
by  a  block  which  is  hinged  at  the  back  and  locked  at  the 
front  by  a  lever  clamp  swivelled  eccentrically.  The  pistons 
have  a  28-inch  stroke.  Through  the  centre  of  each  piston- 
head  is  a  rod  ij  inches  in  diameter,  which  is  screwed  in  the 
base  of  the  press  and  reaches  quite  to  the  top,  and  which  is 
used  as  the  core  to  form  the  detonator  hole  in  the  guncotton 
block.  The  top  of  each  compartment  is  closed  by  a  plate 
perforated  with  holes,  through  which  the  water  which  is 
squeezed  out  of  the  pulp  escapes  and  flows  into  the  reservoir 
between  the  compartments.  The  finished  guncotton  block  is 
2.9  inches  in  diameter,  3}  inches  in  diagonal  (the  corners 
being  chamfered),  and  2  inches  in  height,  and  to  produce  this 
it  is  necessary  that  the  moulded  block  should  be  2.8  inches 
in  diameter,  and  5j  to  5£  inches  high,  when  the  moulding 
pressure  is  100  pounds  to  the  square  inch.  Knowing  the  size 
of  the  compressed  block  desired,  it  is  determined  by  experi- 
ment how  much  of  the  pulp  is  necessary  to  produce  it,  the 
length  of  the  stroke  of  the  piston  being  increased  or  decreased 
to  produce  this  result.  The  pistons  having  been  set,  by 
means  of  the  rod  in  the  centre  of  the  piston-heads,  the  pulp 
is  run  in  until  the  compartment  is  filled,  and  this  is  repeated 
with  each  of  the  four  compartments.  The  perforated  plates 
are  inserted,  the  cover  closed  and  locked,  and  the  pressure 
applied.  The  pressing  occupies  four  minutes.  When  primers 
(smaller  disks  or  blocks)  are  desired  only  one  fourth  the  quan- 
tity of  pulp  is  taken,  and  the  moulded  blocks  have  but  one 
fourth  the  height  of  the  service-blocks. 

Final  Press.  —  This  press  is  a  Sellers  hydraulic  press, 
made  of  steel,  with  an  1 8-inch  ram.  On  the  head  of  the  ram 
are  nine  pistons  which  fit  neatly  into  nine  apertures  in  the 


246  LECTURES   ON  EXPLOSIVES. 

press-block  above  them.  The  press-block  is  made  of  gun- 
bronze,  and  it  is  15  inches  wide,  22  inches  long,  and  7  inches 
thick.  It  is  supported  in  place  by  being  bolted  to  the  verti- 
cal columns  which  support  the  head  of  the  press.  Above  the 
press-block  is  a  travelling-block,  which  is  hung  by  rollers  on  a 
horizontal  track,  so  that  it  may  be  brought  in  contact  with 
the  top  of  the  press-block,  or  pushed  off  from  it  at  will.  Two 
perforated  steel  plates  which  neatly  fit  the  aperture,  one,  which 
is  -J-J-  inch  thick,  above,  and  one,  which  is  one  inch  thick,  below 
the  guncotton  block,  and  these  diaphragms  serve  to  distribute 
the  pressure  uniformly  over  the  surface  of  the  blocks,  while 
the  perforations  allow  the  water  which  is  squeezed  from  the 
block  to  escape.  The  upper  plate  also  bears  on  its  lower  sur- 
face the  marks  which  it  is  desired  to  impress  on  the  block, 
and  thus  serves  as  a  die  to  stamp  the  guncotton. 

A  very  detailed  account  of  the  history  of  each  change  is 
kept  in  the  factory,  and  the  system  of  marking  enables  those 
in  charge  to  keep  track  of  each  charge  until  it  is  expended. 

The  press  is  loaded  by  rolling  off  the  travelling- block,  low- 
ering the  pistons,  dropping  in  the  lower  plates,  then  the 
moulded  guncotton  blocks,  then  the  upper  plates,  and,  finally, 
rolling  the  travelling-block  back  into  place  again.  The  pres- 
sure is  then  applied  by  means  of  a  powerful  hydraulic  pump  in 
a  pit  beside  the  press,  the  safety-valve  of  which  is  set  to  dis- 
charge at  from  1800  to  2000  pounds  as  indicated  by  the  pres- 
sure-gauge. Of  course  the  total  effect  of  the  ram  will  be 
transmitted  to  the  pistons,  and,  as  the  area  of  the  head  of  the 
ram  is  to  that  of  the  nine  pistons'  head  as  3.4  :  I,  the  pressure 
per  square  inch  on  the  guncotton  will  be  6120  pounds  when 
the  initial  pressure  is  1800  and  6800  pounds,  when  the  initial 
pressure  is  2000.  The  pressure  reaches  the  maximum  about 
three  minutes  after  the  pump  is  set  in  operation,  and  this 
pressure  is  maintained  for  about  one  minute  by  the  sand-glass. 
When  the  ram  is  released  the  travelling-block  is  rolled  off,  the 
pump  is  set  at  work  again,  and  the  finished  blocks  of  guncot- 
ton are  pushed  to  the  surface  of  the  press-block.  When 
priming-blocks  are  to  be  pressed,  four  of  the  moulded  blocks 


MANUFACTURE   OF  GUNCOTTON.  247 

are  inserted  in  each  of  the  compartments  of  the  press-block, 
and  they  issue  firmly  compacted  together,  but  showing  dis- 
tinctly the  marks  of  demarcation  of  each  of  the  moulded 
blocks,  and  they  may  be  readily  split  apart  along  these  lines. 
When  the  guncotton  is  taken  from  the  final  press  it  contains 
from  12  to  1 6  per  cent  of  moisture.  It  is  but  natural  to  ap- 
prehend danger  from  subjecting  guncotton  which  is  so  nearly 
dry  to  the  high  pressures  which  are  employed,  especially 
when  we  consider  that  small  particles  of  the  substances  might 
get  pinched  between  the  metal  parts,  and  that  some  of  these 
might  be  air-dried  while  the  press  is  idle.  It  has  been  reported 
that  such  explosions  have  occurred  in  this  way  abroad,  but  it 
has  been  impossible  to  verify  these  reports. 

However,  no  such  explosions  have  thus  far  occurred  at  the 
torpedo  station,  though  the  press-block  was  once  split  open. 
As  far  as  could  be  ascertained,  this  was  due  to  the  workman's 
having  inadvertently  inserted  three  of  the  perforated  plates 
into  one  compartment  and  only  one  into  another,  thus  causing 
the  whole  force  of  the  ram  to  be  exerted  on  one  piston, 
which  bent  and  jammed  and  finally  split  the  block.  The 
guncotton  from  this  pressing  was  recovered  intact  from  the 
press-block.  To  guard  against  serious  results  following  an 
explosion  at  the  station,  the  press  is  surrounded  by  a  rope 
mantlet  (such  as  was  used  in  monitor  turrets  during  the  war 
of  the  rebellion),  which  is  braided  from  Manilla  rope  \\ 
inches  in  diameter.  There  are  four  thicknesses  to  the  mantlet, 
and  this  can  be  relied  upon  to  arrest  pieces  of  the  metal  if 
projected  with  not  too  great  velocity.  When  the  guncotton 
blocks  are  taken  from  the  press  they  are  two  inches  in  height, 
but  after  standing  awhile  they  swell  a  little.  Though  when 
taken  out  they  contain  but  from  12  to  16  per  cent  of  water, 
as  sent  into  the  service  they  contain  about  35  per  cent.  This 
is  added  by  allowing  the  blocks  to  soak  in  a  trough  of  fresh 
water  until  they  cease  to  absorb  water. 

Storage  of  Guncotton. — The  blocks  are  packed  in  the 
torpedo-cases  at  the  guncotton  factory  as  fast  as  they  are 
made,  the  primer-cases  being  filled  with  wet  primers.  A  suf- 


248  LECTURES   ON  EXPLOSIVES. 

ficient  proportion  of  dry  primers  are  sent  with  each  outfit,  and 
when  the  torpedoes  are  desired  for  use  the  wet  priming-blocks 
are  withdrawn  from  the  primer-can  and  dry  ones  substituted. 
These  wet  ones  are  then  dried  by  splitting  the  blocks  apart 
into  J-inch  portions,  weighing  each  one,  stringing  them  on  a 
perfectly  clean  brass  or  copper  rod  or  tube,  separating  the 
blocks  one  from  another,  and  suspending  the  rod  in  a  suitable 
dry  place  (away  from  any  direct  source  of  heat)  where  they 
will  be  freely  exposed  to  air  and  yet  be  under  cover.  The 
blocks  are  to  be  weighed  separately  from  time  to  time,  the 
weights  being  marked  on  each  with  a  soft  lead-pencil,  and 
they  are  to  be  dried  until  they  cease  to  lose  weight. 

NOTE  ON  DRYING  GUNCOTTON. — With  the  adoption  of  smokeless  pow- 
ders, the  great  majority  of  which  contain  guncotton,  it  has  become  neces- 
sary to  devise  a  safe  method  of  drying  this  explosive,  which  under  ordinary 
conditions  of  storage  and  transport  contains  about  30  per  cent  of  moisture. 

On  account  of  its  gradual  decomposition  when  subjected  to  a  continued 
temperature  of  65.5°  C.,  it  has  been  found  to  be  advisable  to  limit  the  max- 
imum temperature  of  the  drying-house  to  46°  C.  An  additional  danger, 
however,  arises  from  the  fact  that  guncotton  possesses  highly  electrical 
properties,  and  the  passage  of  a  current  of  heated  air  over  the  explosive 
may  develop  sufficient  electricity  to  fire  it  ;  in  fact,  several  accidents  which 
have  occurred  in  drying  this  explosive  have  been  attributed  to  this  cause. 

The  most  common  method  of  drying  pulverulent  guncotton  is  to  place 
it  upon  shallow  copper  trays,  which  in  turn  are  placed  upon  racks  in  the 
drying-house.  The  warm,  dry  air  is  introduced  into  the  room  (by  means 
of  a  fan  or  blower)  near  the  ceiling,  circulates  over  and  between  the  trays, 
and  is  drawn  out  by  means  of  an  exhaust  on  a  level  with  the  floor,  the  out- 
lets of  both  air-shafts  being  covered  with  copper  gauze.  The  floor  is  cov- 
ered preferably  with  linoleum,  and  is  also  fitted  with  openings  covered  with 
light  gratings  in  which  the  dust  which  is  unavoidably  formed  during  the 
process  of  drying  is  collected,  and  from  which  it  should  be  carefully  re- 
moved at  regular  intervals. 


LECTURE   XIII. 

SERVICE   TESTS   FOR   GUNCOTTON. 

THERE  are  several  standard  tests  which,  applied  to  gun- 
cotton,  either  during  the  process  of  manufacture  or  at  any 
subsequent  time  to  the  finished  product,  determine  its  chemi- 
cal character.  They  are  as  follows  : 

1.  Determination  of  moisture  in  guncotton 

2.  Determination  of  ash  of  guncotton. 

3.  Test  for  the  presence  of  free  acid. 

4.  Heat  or  stability  test. 

5.  Nitrogen  test. 

6.  Solubility  test. 

7.  Determination  of  unconverted  cotton. 

8.  Determination  of  alkaline  substances. 

9.  Determination  of  temperature  of  ignition. 

Of  these  tests  but  two — the  stability  and  solubility — are 
applied  during  the  process  of  manufacture. 

Preparation  of  Unfinished  Guncotton  for  Testing. — 
Before  applying  the  test  the  guncotton  must  be  carefully 
prepared  beforehand.  In  case  of  the  unfinished  guncotton, 
about  one  quart  of  the  pulp  is  taken  from  the  poacher  after 
having  been  subjected  to  about  six  washings.  As  it  is  of  the 
greatest  importance  that  the  sample  tested  should  represent 
the  average  composition  of  the  charge  in  the  poacher,  it  is 
drawn  in  very  small  quantities  at  a  time,  while  the  revolv- 
ing cylinder  is  in  operation,  and  the  pulp  is  circulating 
actively,  portions  being  taken  from  both  top  and  bottom. 

The  sample  is  allowed  to  stand  until  the  guncotton  has 

249 


250  LECTURES   ON  EXPLOSIVES. 

settled,  when  the  water  is  poured  off,  and  then  one  half  of 
the  guncotton  is  wrapped  in  a  thoroughly  clean  linen  cloth 
and  placed  under  a  hand-press,  where  it  is  subjected  to  a 
tolerably  severe  pressure  for  about  three  minutes,  or  until 
water  ceases  to  flow  from  it. 

The  mass  is  then  taken  out  in  the  form  of  a  cake,  which 
is  broken  up  into  fine  particles  and  rubbed  between  the  hands. 
About  13  gm.  (or  200  gr.)  of  the  guncotton  thus  commi- 
nuted are  placed  in  a  paper  tray,  which  is  placed  on  top  of  a 
water-oven  heated  up  to  120°  F.,  care  being  taken  that  the 
tray  does  not  come  into  contact  with  the  walls  of  the  oven. 
The  mass  is  thus  heated,  with  constant  stirring,  for  fifteen 
minutes.  When  perfectly  dry  the"  sample  is  transferred  to  a 
covered  glass  funnel  with  roughened  sides,  the  neck  of  which 
is  connected  with  a  bellows  through  an  ordinary  aspirator 
bottle.  The  mouth  of  the  funnel  is  covered  with  a  piece  of 
clean  muslin,  and  by  means  of  the  bellows  the  finest  particles 
of  the  guncotton  are  blown  on  the  sides  of  the  funnel,  from 
which  they  are  carefully  removed.  After  these  particles  have 
been  exposed  to  the  atmosphere  of  a  normally  dry  and  warm 
room  for  about  two  hours  the  sample  is  ready  for  testing. 

Preparation  of  Finished  Guncotton  for  Testing. — For 
these  same  tests — stability  and  solubility — the  finished  gun- 
cotton  must  be  prepared  in  a  manner  similar  to  that  just 
described  for  the  pulp.  A  disk  or  block  of  guncotton  is  split, 
and  then  by  gentle  scraping  or  rasping  about  40  grammes 
(or  600  grains)  are  removed  from  the  centre  of  the  mass. 
This  is  placed  in  a  litre  flask  and  a  half-litre  of  distilled  water 
at  a  temperature  of  39°  C.  poured  upon  it,  when  the  flask  is 
corked  and  shaken  vigorously  two  or  three  minutes.  The 
contents  of  the  flask  are  then  filtered  through  muslin,  and 
then,  wrapped  in  the  filter,  are  subjected  to  a  moderate  pres- 
sure in  a  hand-press.  This  operation  is  repeated  three  times, 
when  the  sample  is  dried  and  the  rest  of  the  preparation  is  in 
all  respects  precisely  the  same  as  that  described  for  the  pulp. 

Determination  of  Moisture  in  Guncotton. — The  amount 
of  moisture  in  guncotton  is  readily  determined  by  weighing 


SERVICE    TESTS  FOR   GUNCOTTON.  2$l 

carefully  two  grammes  of  the  cotton  as  it  is  scraped  from  the 
disk  or  block  in  a  watch-crystal,  and  placing  it  in  an  oven  at 
40°  C.  for  twelve  hours,  at  the  end  of  which  time  it  is  placed 
in  a  desiccator  over  sulphuric  acid  and  dried  to  constant 
weight.  The  loss  of  weight  gives  the  moisture,  whence  the 
percentage  of  moisture  is  calculated. 

Determination  of  Ash  of  Guncotton. — This  may  be 
done  as  follows:  Melt  a  little  pure  paraffin  in  a  weighed 
crucible  (porcelain  or  platinum)  by  gentle  heat,  and  add  a 
known  weight  (2  grammes)  of  the  sample.  Ignite  the  mix- 
ture from  above,  and  when  all  is  consumed  ignite  the  cru- 
cible over  a  lamp,  and  then  allow  it  to  cool  and  reweigh. 
The  increase  in  weight  gives  the  ash. 

The  mixture  must  be  ignited  from  above,  and  at  as  low 
a  temperature  as  possible,  to  prevent  the  mass  from  being 
thrown  out  by  an  explosion.  An  incandescent  platinum 
wire  may  be  used  to  ignite  the  mass  in  the  crucible. 

After  as  complete  incineration  as  possible  over  a  lamp  or 
Bunsen  burner,  the  ash  should  be  moistened  with  a  solution 
of  ammonium  carbonate,  and  reignited  several  times  at  200° 
C.  to  constant  weight. 

The  increase  in  the  weight  of  the  crucible  gives  the 
weight  of  ash. 

Test  for  the  Presence  of  Free  Acid. — Put  about  one 
gramme  of  the  cotton  scraped  from  the  disk  in  a  test-tube 
(25  c.c.),  half  fill  the  tube  with  distilled  water,  cork  the  tube 
or  close  it  with  the  thumb,  and  shake  vigorously  for  a  few 
minutes.  Allow  the  cotton  to  settle,  and  test  the  superna- 
tant water  with  litmus  paper,  or,  better,  with  methyl-orange. 
Should  free  acid  in  considerable  quantity  be  found,  the  sub- 
sequent tests  are  unnecessary,  except  as  additional  proofs  of 
the  unsafe  condition  of  the  guncotton. 

Heat  or  Stability  Test. — The  causes  of  the  decomposi- 
tion of  guncotton  have  already  been  alluded  to,  as  well  as  the 
unstable  and  dangerous  condition  of  the  explosive  during  the 
decomposing  stage.  The  object  of  the  heat-test  is  to  deter- 
mine the  exact  character  of  the  guncotton  at  any  time  as 


LECTURES   ON  EXPLOSIVES. 

regards  its  stability.  The  test  itself  depends  upon  the  prin- 
ciple that  when  potassium  iodide  is  decomposed  in  the  presence 
of  starch,  the  iodine  is  liberated  and  reacts  with  the  starch 
to  form  a  colored  body.  This  decomposition  of  potassium 
iodide  is  effected  by  the  oxides  of  nitrogen  and  nitrogen 
acids,  and  in  this  test  the  heat  of  the  bath  drives  off  any  free 
acids  present  in  the  guncotton,  or  decomposes  any  unstable 
bodies,  and  liberates  the  nitrogen  oxides  or  acids,  which  react 
on  the  test-paper,  producing  the  color  referred  to.  As  this 
test  is  applicable  to  all  explosives  containing  the  nitrogen 
oxides  or  acids,  it  will  be  described  at  length. 

Apparatus  and  Materials  required  for  the  Heat-test. 
—  i.  Water-bath. — This  consists  of  a  glass  globe  about  eight 
inches  in  diameter,  which  is  filled  with  water  to  within  a 
quarter  inch  of  the  top  when  the  water  is  heated.  The  globe 
is  open  at  the  top,  and  the  mouth  is  closed  by  a  copper  plate, 
which  is  perforated  with  a  small  hole  in  the  centre  to  receive 
the  thermometer,  and  with  several  holes  about  the  central 
one  of  slightly  larger  diameter  than  that  of  the  test-tubes. 
Around  each  of  these  holes  and  attached  to  the  under  face  of 
the  cover  are  four  spring-clips  inclined  toward  each  other,  so 
that  when  the  test-tubes  are  inserted  in  the  holes  the  clips 
close  firmly  about  them  and  hold  them  in  any  desired  posi- 
tion. The  globe  is  placed  on  strips  of  wood  in  a  metallic 
vessel  about  ten  inches  in  diameter,  and  both  globe  and  bowl 
are  then  filled  with  water.  This  outside  bowl  enables  us  to 
readily  heat  the  apparatus  without  the  danger  of  breaking  the 
glass  globe,  while  the  large  quantity  of  water  is  of  material 
assistance  in  keeping  the  temperature  constant  for  a  consid- 
erable period  of  time. 

2.  Temperature  Regulator  and  Thermometer. — In  making 
the  test  it  is  of  the  greatest  importance  that  during  the 
entire  time  that  the  test-tubes  containing  the  sample  are 
immersed,  the  temperature  should  remain  perfectly  constant. 
Wherever  gas  is  available  for  heating  purposes  in  the  labo- 
ratory, this  is  easily  managed  by  means  of  a  thermostat. 
When  gas- is  not  at  hand,  by  careful  attention  to  the  flame  of 


SERVICE    TESTS  FOR    GUN  COT  TON.  2$< 

either  an  oil-stove  or  spirit-lamp  the  temperature  can  be 
regulated  during  the  test.  The  temperature  is  noted  by 
means  of  an  accurate  thermometer  introduced  into  the  bath 
through  the  central  hole  in  the  cover  of  the  globe. 

3.  Test-tubes. — The   test-tubes   should  be  from    12   to  14 
cm.  long,  and  of  such  diameter  that  each  will  hold  from  20  to 
22  c.c.  of  water  when  filled  to  the  height  of  5  inches.      They 
should  be   marked  with  a   ring,  drawn   around   them  with  a 
diamond,  2 £  inches  from  the  bottom,  and  the  explosive  should 
be  compressed  to  this  mark.      Clean  glass  rods  are  used  for 
pressing  the  guncotton  in  the  tubes.      They  should  be  pro- 
vided with  flat  heads,  and  be  long  enough  to  rea^ch  easily  to 
the  bottom  of  the  tubes. 

4.  Test-paper  Holders. — These  consist  of  small  glass  rods 
about  20  cm.  long,  having  a  piece  of  platinum  wire  about  one 
centimetre  long  fused  into  one  end  and  bent   into  a   hook. 
These  rods  pass  loosely  through  holes  in  taper  corks  which  fit 
neatly  in  the  mouths  of  the  test-tubes. 

5.  Test-papers. — The  test-paper  used  is  known  as  starch 
and  potassium  iodide  paper,  and  is  made  as  follows :    Forty- 
five  grains  of  white  starch,  which  has  been  well  washed  in  cold 
distilled  water  and  thoroughly  dried,  are  added  to  8j-  ounces 
of  distilled  water,  and  the  whole  is  heated  to  boiling,  with 
constant  stirring,  and  is  kept  gently  boiling  for  ten  minutes. 
Fifteen  grains  of   pure  potassum  iodide  (i.e.,  KI,  which  has 
been  recrystallized  from  alcohol)  is  now  dissolved  in  8J  ounces 
of  distilled  water,  and  the  two  solutions  are  mixed  and  allowed 
to  cool.     Strips  or  sheets  of  fine  white  filter-paper,  which  have 
been  previously  washed    in  distilled  water   and   redried,   are 
dipped  in  the  above  solution  and  allowed  to  remain  in  it  for 
not  less  than  ten  seconds,  when  they  are  removed  and  hung 
up  to  dry  in  a  warm,  dark  room  which  is  free  from  laboratory 
dust  and  fumes.      When  dry,  the  upper  and  lower  margins  of 
the  strips  or  sheets  are  cut  off  and  the  paper  is  preserved  in 
well-stoppered,   dark-colored   bottles,   or   in   ordinary  bottles 
which  are  kept  out  of  contact  with  the  direct  rays  of  light. 
For  use  in  makihg  the  test,  the  paper  is  cut  into  small  rec- 


254  LECTURES   ON  EXPLOSIVES. 

tangular  pieces,  10  mm.  by  20  mm.  (about  T\  by  T8¥  of  an 
inch).  They  are  attached  to  the  test-paper  holders  by 
piercing  them  near  the  top  with  the  point  of  a  knife,  two 
incisions  being  made  at  right  angles  to  each  other  forming  a 
cross.  The  point  of  the  platinum  wire  is  inserted  through 
the  centre  of  the  cross,  and  the  hook  is  bent  firmly  together 
so  as  to  hold  the  papers  rigidly  in  line  with  the  rod  of  the 
holder. 

6.  Glycerine  Solution. — This  is  made  by  dissolving  ten  per 
cent  of  pure  glycerine  in  distilled  water.    It  is  kept  in  a  small 
flask,  the  mouth  of  which  is  closed  by  a  cork,  and  the  latter 
is  perforated  to  receive  a  small  glass  rod  which  is  long  enough 
to  reach  the  bottom  of  the  flask,  and  drawn  to  a  point  at  its 
lower  end.      The  glycerine  solution   is  used  to   moisten  the 
test   paper,  and   is  applied  by  holding  the  test-paper  holder 
vertically  with  the  paper  uppermost,  and  then  touching  the 
paper  at  the  edge  where  it  is  fastened  to  the  platinum  hook, 
with  the  rod  just  as  it  is  drawn  from  the  solution.      Enough 
solution  is  applied  to  thoroughly  moisten  the  paper  across  its 
entire  width  and  for  one  half  its  length.      The  holder  is  held 
with  the  paper  upward  until  the  solution  has  been  drawn  by 
capillarity  up  to  the  middle  of  the  paper,  and  is  found  to  go 
no  further. 

7.  Standard  Tint-paper. — As  in  all  tests  depending  upon 
a  comparison  or  determination  of  color  considerable  difficulty 
is  encountered  practically  in  conducting  the  heat  test,  especially 
by  inexperienced  operators.      And  since  it  is  of  the  greatest 
importance  that   the  exact  moment  at  which  the  coloration 
upon  the  test-paper  reaches  the  proper  depth  or  shade  should 
be  noted,  a  standard  tint-paper  has  been  devised  to  aid  ob- 
servers in  this  determination. 

It  is  prepared  by  making  a  caramel  solution  in  distilled 
water  of  such  concentration  that  when  diluted  one  hundred 
times  (10  c.c.  made  up  to  a  litre)  the  tint  of  the  solution 
equals  that  produced  by  the  Nessler  test  (2  c.c.)  in  100 
c.c.  of  water  containing  0.000075  gramme  of  ammonia,  or 
0.00023505  gramme  of  ammonium  chloride.  With  this  solu- 


SERVICE    TESTS  FOR   GUNCOTTON.  255 

tion  lines  are  drawn  on  slips  of  white  filter-paper  by  means  of 
a  clean  quill  pen.  When  the  slips  are  dry  they  are  cut  into 
pieces  of  the  same  size  as  the  test-papers,  and  in  such  a  way 
that  each  piece  has  a  brown  line  across  it  near  the  middle  of 
its  length,  and  only  those  strips  are  preserved  in  which  the 
brown  line  has  a  breadth  varying  from  -J-  to  I  mm.  (fa  to  fa  of 
an  inch).  This  may  be  used  by  hanging  a  strip  in  a  test-tube 
beside  the  tube  in  which  the  test  is  being  made,  and  noting 
each  until  a  brown  (or  yellow)  line  appears  on  the  test-paper, 
similar  in  depth  or  shade  to  that  in  the  standard  tint-paper. 
I  consider  the  use  of  standard  tint-paper  of  doubtful  value, 
the  only  true  and  reliable  guide  being  experience. 

How  to  Make  the  Heat  Test.— Insert  the  thermometer 
in  the  bath  to  a  depth  of  about  three  inches,  and  apply  the 
heat  until  the  temperature  is  constant  at  65°. 5  C.  (150°  F.). 
The  weighed  sample  of  guncotton  (20  grains)  is  introduced 
into  the  tube  and  pressed  down  by  means  of  the  glass  rod  to 
the  mark,  and  the  tube  is  closed  with  a  loosely-fitting  cork. 
The  tube  is  then  inserted  in  the  bath  until  the  upper  surface 
of  the  sample  coincides  with  the  level  of  the  water,  and  the 
fxact  time  of  insertion  is  noted.  The  test-paper  is  now  moist- 
ened with  the  glycerine  solution,  the  paper  being  drawn  up 
•close  to  the  bottom  of  the  cork.  The  holder  with  the  test- 
paper  attached  is  substituted  for  the  cork  in  the  test-tube. 
Shortly  after  the  test-tube  has  been  introduced  into  the  bath, 
a  ring  of  moisture  will  begin  to  form  in  the  upper  part  of  the 
tube.  As  soon  as  this  is  observed,  the  test-paper  is  lowered 
by  pushing  the  rod  through  the  cork  until  the  line  of  demar- 
cation between  the  wet  and  dry  portions  of  the  paper  is  coinci- 
dent with  the  lower  edge  of  the  ring  of  moisture.  The  test- 
paper  is  now  closely  watched,  and  as  soon  as  the  faintest  sign 
of  discoloration  appears  on  the  test-paper  (and  it  appears  at  the 
line  of  demarcation  between  the  wet  and  dry  portions),  the 
time  is  again  noted.  When  the  standard  tint- paper  is  used, 
the  second  time  is  taken  when  the  two  colors  (that  on  the 
test-paper  and  that  on  the  standard  tint-paper)  are  of  precisely 
the  same  depth  or  shade. 


256  LECTURES   ON  EXPLOSIVES. 

The  time  elapsed  for  stable  guncotton  must  not  be  less 
than  fifteen  (15)  minutes.  In  the  U.  S.  Artillery  School  Lab- 
oratory it  is  customary  to  make  three  tests  of  each  sample  at 
the  same  time,  using  as  many  tubes,  and  introducing  them  in 
rapid  succession,  so  that  the  conditions  may  be  practically  the 
same  and  the  mean  of  the  three  tests  is  taken.  The  record  is 
kept  as  follows: 

U.  S.  ARTILLERY  SCHOOL, 

DEPARTMENT  OF  CHEMISTRY  AND  EXPLOSIVES, 

January  23,  1890. 

HEAT   TEST   OF    GUNCOTTON. 
Sample :  Torpedo  Station,  Charge  100,  1889. 

i.  2.  3. 

Time  of  stopping ....   10.51         10.53         JO-55 

Time  of  starting.. 10.30         10.33         10.38 

Time  elapsed. .. 21  20  17 

Mean 19  m.  20  s. 

Condition  of  sample  :   Stable. 


....  Lieutenant,  ....   U.S.  Artillery, 

Operator. 

Nitrogen  Test  —  This  test  depends  upon  the  principle 
chat  when  cellulose  nitrates  are  treated  with  pure  concentrated 
sulphuric  acid  in  the  presence  of  mercury,  they  are  decomposed, 
all  of  the  nitrogen  being  evolved  in  the  form  of  nitrogen  oxides, 
which  may  'be  collected  and  measured,  whence  the  percentage 
of  nitrogen  may  be  easily  calculated.  Should  the  nitrate 
under  examination  be  the  tri-nitrocellulose,  the  reaction 
would  be  represented  as  follows: 


2(C6H702)03(N02)3  +  QH2S04  +  i8Hg  = 
2(C6H,O2)O3H3  +  9Hg2SO4  +  6H2O  +  6NO. 

Similar  equations  may  be  written  to  represent  the  reactions 
which  occur  in  the  cases  of  the  other  nitrates,  and  from  the 
percentage  of  nitrogen  found  we  are  able  to  decide  very 
approximately  the  particular  nitrate,  the  presence  of  which  is 
the  cause  of  trouble. 

The  test   is  easily  made  by  means  of  a  nitrometer,    the 
form  used  in   the  Artillery  School  Laboratory  being  that  de- 


SERVICE    TESTS  FOR   GUNCOTTON.  2 $7 

vised  by  Bunte  for  gas  analysis.  This  apparatus  consists  of 
two  glass  tubes  of  about  150  c.c.  capacity,  connected  at  their 
lower  ends  by  means  of  a  rubber  tube.  The  upper  end  of 
one  of  the  tubes  is  fitted  with  a  thistle-bulb  funnel,  between 
which  and  the  tube  proper  is  a  three-way  stop-cock ;  there  is 
also  an  ordinary  stop-cock  fitted  at  the  lower  end  of  this  tube, 
This  tube,  which  is  called  the  burette,  is  graduated  into 
tenths  of  cubic  centimetres,  while  the  other  tube,  called  the 
filling  tube,  is  ungraduated.  Both  tubes  are  mounted  in  a 
burette-holder  so  as  to  be  vertical  and  side  by  side,  but  either 
may  be  raised  or  lowered  at  will.  To  conduct  the  test,  the 
nitrometer  is  first  filled  as  follows:  The  rubber  tube  having 
been  securely  attached,  the  graduated  tube  is  firmly  clamped 
in  the  burette-holder  and  both  stop-cocks  opened;  then, 
holding  the  plain  tube  in  the  left  hand  so  that  it  is  raised 
about  two  thirds  of  its  length  above  the  graduated  one,  pour 
into  the  nitrometer  through  a  funnel  fitted  in  the  plane  tube 
enough  mercury  to  completely  fill  the  graduated  tube  and 
partially  fill  the  plain  one.  Then  close  the  upper  stop-cock 
of  the  graduated  tube  and  secure  the  plain  tube  in  the  burette- 
holder  alongside  of  the  former  and  on  a  level  with  it.  Next 
introduce  into  the  funnel  at  the  top  of  the  burette  300  milli- 
grammes of  thoroughly  dried,  finely  divided  guncotton,  and 
cover  it  with  5  c.c.  of  pure  concentrated  sulphuric  acid.  The 
upper  stop-cock  is  then  very  carefully  opened,  and  the  mix- 
ture is  swept  into  the  tube,  additional  acid  being  added  to 
wash  every  particle  of  the  guncotton  into  the  tube.  It  re- 
quires the  most  careful  manipulation  at  this  point  in  order  that 
the  flow  of  acid  may  be  constant  and  that  no  air  gets  into  or 
gases  escape  from  the  tube,  in  either  of  which  events  the 
results  are  vitiated. 

It  is  well  to  have  an  excess  of  acid  so  that  the  stop-cock 
may  be  closed  before  the  last  traces  of  the  acid  run  into  tube. 
The  reaction  begins  as  soon  as  the  mixture  reaches  the  mer- 
cury, and  is  assisted  from  time  to  time  by  closing  the  lower 
stop-cock  of  the  burette,  removing  it  from  its  clamp  and 
shaking  it  carefully.  After  the  reaction  has  entirely  ceased 


258  LECTURES   ON  EXPLOSIVES. 

(usually  at  the  end  of  one-half  hour),  the  tubes  are  adjusted 
so  that  the  mercury  in  each  is  at  the  same  height,  and  the 
exact  amount  of  acid  in  the  burette  noted.  The  filling-tube 
is  then  raised  so  that  the  level  of  the  mercury  in  it  is  higher 
than  that  in  the  burette  by  one  seventh  of  the  number  of 
divisions  in  the  burette  occupied  by  the  sulphuric  acid  and 
the  volume  of  the  gas  is  read  off.  The  tubes  are  again  placed 
side  by  side,  and  allowed  to  stand  for  fifteen  minutes,  when 
the  volume  of  gas  is  verified  by  adjusting  the  tubes  as  before. 
When  the  readings  become  constant,  the  thermometer  and 
barometer  are  noted  and  the  volume  of  the  gas  is  reduced  to 
o°  C.  and  76  cm.  by  Charles'  and  Mariotte's  laws,  which  may 
be  conveniently  written  as  follows  : 


in  which  Vt  represents  the  volume  of  the  gas  at  the  observed 

temperature  ; 

F0  represents  the  volume  of  the  gas  at  o°  C.  ; 
Pt  represents  the  observed  pressure   of   the   atmos- 

phere at  the  time  of  the  experiment  ; 
Pa  represents  the  pressure  of  the  atmosphere  at  76 

cm.  ; 

t  represents  the  observed  temperature  at  the  time 
of  the  experiment. 

The  weight  of  the  sample  being  known,  from  the  data 
obtained  from  the  methods  given  above,  the  weight  of  nitro- 
gen present  and  the  percentage  in  the  guncotton  are  readily 
calculated  according  to  the  formula  assumed  to  represent  mili- 
tary guncotton.  Thus,  if  we  accept  the  results  of  Eder's 
investigations,  and  assume  the  formula  (C12H,4O4)O8(NO2)6  to 
represent  the  highest  degree  of  nitration  possible,  the  per- 
centage of  nitrogen  cannot  exceed  14.14,  and  allowing  for 
errors  due  to  manipulation,  etc.,  it  should  not  fall  below 
13.665.  If,  on  the  other  hand,  Vieille's  formula,  (C34H29O9) 
On.(NO2)n  ,  represent  military  guncotton,  which  is  always 


SERVICE    TESTS  FOR   GUNCOTTON. 

assumed  to  be  the  most  highly  nitrated  product  attainable, 
the  highest  percentage  of  nitrogen  to  be  obtained  cannot 
exceed  13.496,  and,  with  the  same  allowance  for  personal 
errors  of  the  operator,  should  not  be  less  than  12.996. 

Solubility  Test. — This  test  depends  upon  the  principle 
that  the  lower  cellulose  nitrates  are  soluble  in  a  mixture  of 
ether  and  alcohol,  while  the  tri-nitrocellulose  is  insoluble  in 
such  a  mixture.  This  test  logically  follows  that  just  described 
exactly  as  the  heat  test  follows  that  for  the  presence  of  free 
acid.  By  this  test  we  determine  the  presence  or  absence  of 
the  lower  or  unstable  nitro-compounds,  and  taken  in  connec- 
tion with  the  nitrogen  test,  which  will  be  described  later,  we 
are  able  to  determine  very  closely  which  particular  compound 
is  the  cause  of  trouble,  and  therefore  the  exact  character  of 
the  explosive. 

About  20  grammes  of  the  pulp  from  the  poacher,  or  10 
grammes  of  the  finished  product,  are  treated  in  the  hand-press 
as  described  for  the  heat  test,  and  the  cake  is  then  broken  up 
and  placed  in  an  air-bath,  where  it  is  dried  at  a  temperature  of 
40°  C.  for  about  two  hours,  being  rubbed  between  the  hands 
occasionally  to  break  up  the  lumps.  When  well  dried  it  is 
removed  from  the  bath  and  exposed  to  the  air  for  an  hour. 
Two  grammes  of  the  sample  thus  prepared  are  weighed  out  in 
a  watch-crystal  and  carefully  introduced  into  a  flask,  and 
covered  with  four  fluid  ounces  of  a  mixture  of  one  volume  of 
absolute  alcohol  (sp.  gr.  0.805)  and  two  volumes  of  Squibbs' 
strongest  ether  (sp.  gr.  0.735).  The  flask  is  then  corked  and 
shaken  at  intervals  for  two  hours.  At  the  end  of  that  time  the 
contents  of  the  flask  are  decanted  upon  a  weighed  linen  or 
muslin  filter  (which  has  been  previously  washed  in  some  of  the 
ether-alcohol  mixture)  and  washed  on  the  filter  with  four 
ounces  more  of  the  mixture;  the  filter  and  contents  are  then 
squeezed  thoroughly  to  remove  any  of  the  solution  present. 
(The  funnel  in  which  the  filter  is  placed  is  introduced  into  a 
perfectly  clean  bottle,  so  that  the  mixture  may  be  saved  for 
distillation  and  future  use.)  The  residue  in  the  filter  is  care- 
fully removed  by  means  of  a  glass  spatula,  and  is  replaced  in 


260  LECTURES   ON  EXPLOSIVES. 

the  flask  and  covered  with  four  ounces  of  fresh  ether-alcohoL 
The  flask  is  again  corked  and  shaken  at  intervals  for  one-half 
hour,  and  the  contents  are  then  decanted  upon  the  same  filter 
as  before  and  washed  with  four  ounces  more  of  the  ether-alco- 
hol mixture.  The  filter  is  again  squeezed,  and  then,  with  its 
contents,  is  spread  upon  a  perfectly  clean  glass  plate,  and 
placed  in  a  drying  oven  and  heated  until  all  odor  of  the  alco- 
hol has  disappeared.  It  is  then  exposed  to  the  air  for  two 
hours  and  weighed.  The  drying  and  exposure  to  the  air  are 
repeated  until  the  weight  is  constant.  The  difference  between 
the  weight  of  the  guncotton  taken  and  that  of  the  residue 
found  gives  the  weight  of  the  substance  dissolved,  whence  the 
percentage  is  readily  calculated.  The  soluble  matter  in  gun- 
cotton  should  not  exceed  10  per  cent.  The  guncotton  made 
at  the  U.  S.  Naval  Torpedo  Station  contains  usually  less  than 
6  per  cent. 

On  account  of  the  expense,  it  is  usual  to  take  the  mean 
of  two  tests  at  the  U.  S.  Artillery  School  Laboratory  as  suffi- 
cient to  establish  the  percentage  of  soluble  matter,  unless  the 
discrepancy  between  the  two  is  such  as  to  render  doubtful  the 
accuracy  of  either  result,  in  which  case  a  third  and  possibly 
a  fourth  determination  is  made. 

The  record  is  kept  as  follows : 

U.  S.  ARTILLERY  SCHOOL, 

DEPARTMENT  OF  CHEMISTRY  AND  EXPLOSIVES, 
January  27,  1890. 

SOLUBILITY   TEST   OF   GUNCOTTON. 
Sample  :  Torpedo  Station,  Charge  100,  1889. 

I.  2. 

Weight  of  sample  (in  milligrammes) 2,000  2,000 

Weight  of  filter 2,955  3,008 

Weight  of  sample  and  filter 4,955  5, 008 

Weight  of  insoluble  guncotton  and  filter 4,821  4,891 

Weight  of  soluble  guncotton 134  117 

Mean 125-5 

Percentage  of  soluble  guncotton 6.275 


.Lieutenant U.  S.  Artillery, 

Operator. 


SERVICE    TESTS   FOR   GUNCOTTON.  26 1 

Test  for  Unconverted  Cotton. — Besides  the  determina- 
tion of  the  soluble  guncotton,  it  is  sometimes  necessary  to 
determine  the  amount  of  unconverted  cellulose  present.  This 
may  be  done  by  treating  the  residue  from  the  ether-alcohol 
washing  with  ethyl  acetate  (acetic  ether).  By  digestion  with 
this  solvent  the  cellulose  nitrates  are  dissolved,  and  the  un- 
converted cellulose  is  left  behind  and  may  be  collected  on  a 
weighed  filter.  Or  it  may  be  treated  by  boiling  with  a 
solution  of  sodium  stannate  made  by  adding  caustic  soda  to 
a  solution  of  stannous  chloride  until  the  precipitate  at  first 
formed  is  just  redissolved.  This  solution  dissolves  the  cellu- 
lose nitrates,  but  does  not  affect  cellulose. 

Determination  of  Alkaline  Substances.  —  For  certain 
purposes  it  is  often  desirable  to  know  the  amount  of  calcium 
and  sodium  compounds  present  in  the  finished  guncotton. 
For  this  test  five  (5)  grammes  of  air-dried  guncotton  are  taken 
from  the  centre  of  a  disk  or  block,  rubbed  up  finely,  and 
extracted  by  means  of  100  c.c.  of  standard  hydrochloric  acid 
diluted  with  about  twice  its  volume  of  water.  The  guncotton 
and  acid  are  allowed  to  digest  together  for  a  short  time,  the 
liquid  is  decanted,  and  the  guncotton  washed  either  by  decan- 
tation  or  upon  a  filter,  until  the  washings  exhibit  no  acid 
reaction.  The  washings  are  added  to  the  decanted  liquid, 
and  100  c.c.  of  standard  sodium  carbonate  solution  is  poured 
in.  The  amount  of  sodium  carbonate  neutralized  is  deter- 
mined by  titrating  with  the  standard  acid  solution,  using 
litmus  or  methyl-orange  as  an  indicator.  The  amount*  of 
alkalies  in  the  guncotton  is  measured  by  the  amount  of  un- 
neutralized  sodium  carbonate.  The  standard  sodium  carbo- 
nate solution  may  be  prepared  by  dissolving  3  grammes  of  the 
salt  in  100  c.c.  of  distilled  water,  or  the  standard  alkaline  and 
acid  solutions  may  be  so  constructed  that  equal  volumes  will 
neutralize  each  other. 

Determination  of  the  Temperature  of  Ignition. — Gun- 
cotton,  when  properly  made,  should  not  ignite  below  180°  C. 
To  determine  the  point  at  which  guncotton  ignites,  put  about 
0.05  gm.  in  a  strong  test-tube,  and  suspend  the  tube  in 


262  LECTURES   ON  EXPLOSIVES. 

an  oil-bath  previously  heated  to  100°  C.,  and  gradually  in- 
crease the  temperature  of  the  oil  until  the  guncotton  flashes. 
Note  the  temperature  of  the  bath  by  means  of  a  thermometer, 
the  bulb  of  which  is  immersed  in  the  oil.  The  temperature 
of  ignition  varies  according  as  the  heating  is  gradually  or  sud- 
denly applied ;  and  in  order  to  determine  the  temperature  of 
ignition  when  the  guncotton  is  suddenly  heated,  an  oil-bath 
fitted  with  a  top  containing  six  or  more  openings  for  test- 
tubes  and  a  central  hole  to  receive  a  perforated  cork,  through 
which  the  bulb  of  a  thermometer  projects  into  the  oil  below, 
may  be  used.  As  the  temperature  of  the  oil  is  raised  by 
heating  from  below,  minute  quantities  of  guncotton  are  intro- 
duced into  the  tubes,  and  the  temperature  at  which  it  flashes 
is  noted  on  the  thermometer. 


LECTURE    XIV. 

NITRIC   ETHERS — NITROGLYCERINE. 

NITRIC  ethers  are  obtained  by  the  action  of  nitric  acid 
upon  simple  alcohols,  the  reactions  being  represented  by 
equations  similar  in  every  respect  to  those  representing  the 
formation  of  nitric  esters. 

As  distinguished  from  nitro-substitution  compounds,  they 
possess  the  general  characteristics  of  nitric  derivatives,  in- 
cluding the  arrangement  of  the  atoms  in  their  molecular 
structure,  as  enumerated  in  previous  lectures. 

Nitric  ethers  differ  from  nitric  esters  in  that,  when  the 
latter  are  treated  with  reducing  agents,  the  original  ingredi- 
ents are  only  partially  reproduced,  the  acid  being  destroyed ; 
whereas  by  subjecting  nitric  ethers  to  the  prolonged  action  of 
water  and  dilute  alkalies,  both  the  original  acid  and  alcohol 
are  entirely  reproduced. 

Nitroglycerine. — This  powerful  explosive  may  be  taken 
as  the  representative  of  the  class  of  nitric  ethers. 

Discovery  and  Early  History. — The  discovery  of  the  fact 
that  cotton,  when  immersed  in  nitric  or  in  a  mixture  of  nitric 
and  sulphuric  acids,  was  converted  into  a  highly  explosive 
substance  gave  rise  to  a  warm  controversy  among  the  chem- 
ists of  the  day  as  to  the  nature  of  the  change  which  had 
taken  place,  one  party  holding  that  the  change  was  a  true 
chemical  one,  and  was  due  to  the  substitution  of  certain  of 
the  components  of  the  nitric  acid  for  certain  components  of 
the  cotton,  resulting  in  the  formation  of  a  new  compound 

263 


264  LECTURES   ON  EXPLOSIVES. 

substance ;  while  the  other  party  held  that  it  was  physically 
impossible  that  so  delicate  a  material  as  cotton-fibre  could 
change  its  elements  without  a  more  obvious  change  of  struc- 
ture, and  that  the  change  was  simply  a  physical  one  due  to 
the  absorption  of  the  nitric  acid  in  the  pores  of  the  cotton, 
just  as  nitre  is  absorbed  by  paper  in  the  manufacture  of 
touch-paper,  and  that  thus  the  inflammability  of  the  sub- 
stance was  increased. 

It  is  obvious  that  with  such  a  difference  of  views  prevail- 
ing the  true  one  could  only  be  established  by  experimental 
evidence,  and  hence  the  promulgation  of  these  views  led  to 
many  experiments  being  made  upon  a  large  number  of  sub- 
stances which  were  analogous  in  their  chemical  characters  to 
cotton.  Pelouze,  the  French  chemist,  was  one  of  the  more 
active  advocates  of  the  theory  of  exchange,  and,  among 
other  experiments,  he  suggested  to  his  pupil  Sobrero  that  he 
should  study  the  effects  of  nitric  acid  on  glycerine,  because, 
as  the  latter  was  chemically  analogous  to  cotton,  it  was  prob- 
able that,  if  the  change  was  a  chemical  one,  an  explosive 
body  would  be  formed,  and  it  was  obvious  that  if  an  explo- 
sive body  was  formed  it  must  be  due  to  replacement,  for  it 
was  exceedingly  unlikely  that  a  liquid  like  glycerine  could 
absorb  and  retain  in  its  pores,  by  mere  physical  force,  a  liquid 
like  nitric  acid. 

Sobrero  made  the  experiment  and  discovered  nitroglycer- 
ine, which  announced  its  birth  by  a  violent  explosion  which 
shattered  the  windows  of  the  laboratory  and  wrecked  the 
apparatus. 

The  great  power  which  this  explosive  exhibited  and  the 
apparent  readiness  with  which  it  exploded  conspired  to  make 
chemists  somewhat  reluctant  to  pursue  the  investigation  of 
the  character  and  properties  of  this  substance ;  and  so,  al- 
though Sobrero  made  his  discovery  in  1846,  little  was  done 
with  it  until  the  Crimean  War,  when  it  was  asserted  that 
Professor  Jacobi  had  manufactured  the  explosive  in  quantities 
for  the  Russian  Government,  and  that  its  reputed  presence 
deterred  the  English  from  entering  the  harbor  of  Cronstadt, 


NITRIC  ETHERS— NITROGLYCERINE.  26$ 

though  during  this  time  it  was  employed  in  very  small  quan- 
tities as  a  medicinal  agent  under  the  name  of  glonoine. 

The  practical  use  of  the  substance  as  an  explosive  agent 
is  due  to  Alfred  Nobel,  a  Swedish  engineer,  whose  name  is 
indissolubly  connected  with  and  pre-eminent  in  the  history 
of  nitroglycerine  explosives,  and  who,  about  1860,  invented 
a  process  for  its  rapid  manufacture,  which  he  patented  under 
the  name  of  detonating  oil,  or  Nobel 's  Sprengcel,  and  between 
this  and  1863  established  factories  on  the  continent  of  Eu- 
rope for  its  manufacture  on  a  commercial  scale. 

At  this  time  Nobel  used  the  same  means  for  exploding 
the  substance  as  were  employed  for  firing  gunpowder,  with 
the  addition,  sometimes,  of  a  priming-charge  of  gunpowder; 
but  it  was  found  that,  even  when  confined,  the  nitroglycerine 
was  but  partially  exploded.  In  1863,  however,  he  discovered 
that  it  could  not  only  be  exploded  with  certainty  by  means 
of  a  cap  containing  mercury  fulminate,  but  that  the  power 
developed  when  thus  exploded  was  enormously  greater  than 
•could  be  obtained  from  it  by  any  other  means.  The  dis- 
covery of  this  fact  marks  not  only  an  epoch  in  the  history  of 
nitroglycerine,  but  in  that  of  all  explosives,  since  it  revealed 
to  us  the  method  of  inducing  explosion  by  detonation. 

Great  expectations  were  aroused  by  the  announcement 
that  the  enormous  force  stored  up  in  nitroglycerine  was 
completely  under  control  and  could  be  used  at  will  for  doing 
useful  work,  and  it  found  its  way  to  the  scene  of  mining 
operations  in  many  parts  of  the  world. 

The  introduction  of  nitroglycerine  into  the  United  States 
was  attended  with  numerous  and  severe  explosions,  which 
for  some  time  discouraged  the  earlier  experimenters  in  this 
country. 

But  it  was  observed  that  these  accidental  explosions  were 
exceptional,  and  that  in  repeated  instances  nitroglycerine  had 
been  transported  long  distances  both  by  sea  and  by  land,  and 
had  been  stored  for  considerable  periods  of  time  without 
undergoing  explosion;  and,  as  the  agent  was  too  valuable  a 
one  to  be  abandoned  if  its  safety  could  be  in  any  way  in- 


266  LECTURES   ON  EXPLOSIVES. 

sured,  several  chemists  were  encouraged  to  further  investigate 
its  properties,  and  to  seek  to  discover  and  remove  the  causes 
which  had  operated  to  produce  these  premature  explosions. 
Notable  among  these  investigators  were  the  American  chem- 
ists Mowbray  and  Hill,  and  through  their  efforts  the  difficul- 
ties attending  the  production  of  a  pure  and  stable  substance 
have  been  surmounted,  so  that  for  many  years  past  nitro- 
glycerine has  been  manufactured,  stored,  transported,  and 
used  with  comparative  safety,  and  with  less  attendant  danger 
than  surrounds  gunpowder. 

Chemistry  of  Nitroglycerine. — The  manufacture  of  nitro- 
glycerine is  based  upon  the  reaction  which  takes  place  when 
glycerine  is  brought  in  contact  with  nitric  acid,  and  which 
may  be  represented  by 

C,H.O,H,  +  3HONO,  =  C,H.O.(NO,).  +  3H.O, 

in  which  one  molecule  of  glycerine  being  acted  upon  by  three 
molecules  of  nitric  acid  yields  one  molecule  of  tri-nitroglyc- 
erine  (or,  better,  glyceryl  tri-nitrate)  and  three  molecules  of 
water,  three  atoms  of  hydrogen  in  the  glycerine  being 
replaced  by  the  three  atoms  of  nitryl  (NOa)  in  the  three 
molecules  of  nitric  acid. 

It  is  believed  to  be  possible  to  produce  three  different 
nitroglycerines.  By  replacing  one  atom  of  hydrogen  in  the 
glycerine  by  one  atom  of  nitryl  the  mono-nitroglycerine  is 
formed,  having  the  formula  C8H6O3(NO2)H2.  By  replacing 
two  of  the  atoms  of  hydrogen  by  two  of  nitryl  the  di-nitro- 
glycerine  is  produced,  having  the  formula  C3H6O3(NO2)UH. 
By  replacing  the  three  atoms  we  get  the  tri-nitroglycerine 
given  in  the  reaction  above. 

By  writing  the  formula  for  glycerine  as  a  trihydric 
§ alcohol,  and  as  in  the  case  of  cellulose,  assuming  that  in  the 
substitution  of  nitryl  for  hydrogen  in  the  formation  of  nitro- 
glycerine only  the  hydrogen  atoms  combined  as  hydroxyl 
are  replaceable,  the  same  reason  assigned  for  the  limited 
degree  of  nitration  in  the  case  of  the  nitrocelluloses  is  appli- 


NITRIC  ETHERS— NITROGLYCERINE.  267 

cable  to  the  nitroglycerol,  and  the  molecular  arrangement  may 
be  represented  by  the  following  structural  formulae: 

H       H       H 
H— C— C— C— H 

A  A  i 


Glycerine— CSH6(OH)3. 

H      H      H  H       H      H 

III  III 

H  —  C  —  C  —  C  —  H  H  —  C  —  C  —  C  —  H 

O       O       O  O       O       O 

I         I         I  III 

H       N       H  N       H       N 

/A\  A         A 

00  0000 

Mono-nitroglycerine —  Di-nitroglycerine — 

C3H503.(N02)H3.  C3H603(N02)2H. 

H      H  H 

I         I  I 
H— C— C— C— H 

I  I 

O  O 


v^ 

A 


N       N       N 

A    A    /A\ 

000000 

Tri-nitroglycerine — CsH6O 

The  term  nitroglycerine  is  misleading,  and  has  caused 
many  errors  to  be  made  upon  the  assumption  that  this  nitric 
derivative  belongs  to  the  class  of  nitro-substitution  products, 
instead  of  being  typical  of  the  nitric  ethers. 

A  more  correct  name  for  the  new  explosive  would  have 
been  glyceryl  tri-nitrate,  or  nitric  glyceride. 

The  name  nitroglycerine  has  been  so  generally  accepted, 
however,  that  it  is  practically  impossible  to  change  it ;  but  it 
is  well  to  remember  that  in  no  way  can  it  be  considered  as  a 


268  LECTURES   ON  EXPLOSIVES. 

nitro-compound,  but,  for  reasons  already  given,  belongs  to 
the  class  of  nitric  ethers,  a  subclass  of  nitric  derivatives. 

It  is  believed  also  that  the  tri-nitroglycerine  is  the  only 
one  of  the  three  derivatives  mentioned  which  is  stable,  and 
that  many  of  the  accidents  which  have  been  caused  by  nitro- 
glycerine have  been  due  to  the  presence  of  these  other  com- 
pounds in  the  tri-nitroglycerine. 

To  produce  pure  nitroglycerine  it  is  necessary  that  we 
should  use  the  purest  anhydrous  glycerine  and  the  purest  and 
strongest  nitric  acid.  The  presence  of  any  fatty  impurities 
in  the  glycerine  gives  rise  to  the  formation  of  unstable  bodies 
which  cause  the  decomposition  and  spontaneous  explosion  of 
the  nitroglycerine,  while  the  presence  of  iron,  alumina,  or 
chlorine  seriously  interferes  with  the  separation  of  the  nitro- 
glycerine. It  has  been  difficult  to  obtain  anhydrous  glycer- 
ine and  anhydrous  nitric  acid ;  hence  it  is  the  custom  to  use 
the  most  concentrated  articles  to  be  obtained  and  to  mix 
with  them  some  substance  which  will  absorb  the  water  present 
and  thus  render  them  anhydrous.  The  importance  of  using 
an  exsiccating  substance  is  further  shown  if  we  refer  to  the 
reaction,  by  the  fact  that  water  is  one  of  the  products  of  the 
reaction,  and  hence,  if  we  were  to  start  with  anhydrous 
glycerine  and  nitric  acid,  after  a  portion  of  the  glycerine  has 
been  converted,  the  water  formed  will  have  so  diluted  the 
remainder  that  there  is  danger  of  the  lower  nitric  ethers  being 
formed.  Concentrated  sulphuric  acid  is  used  as  the  exsic- 
cating substance,  and  it  is  added  in  sufficient  quantity  to 
combine  not  only  with  the  water  contained  in  the  original 
substances,  but  also  with  all  the  water  formed  during  the 
operation. 

But  in  using  the  sulphuric  acid  an  element  of  danger  is 
introduced.  The  sulphuric  acid  removes  the  water  by  enter- 
ing into  chemical  combination  with  it,  a  hydrate  of  sulphuric 
acid  being  formed,  and  this  combination  is  attended  with  the 
development  of  heat.  If  the  temperature  is  raised  much 
above  30°  C.  there  is  danger  of  the  nitroglycerine  being  ex- 
ploded, or  if  an  explosion  does  not  result,  the  glycerine  will 


NITRIC  ETHERS— NITROGLYCERINE.  269 

be  wasted  by  being  converted  into  oxalic  acid  and  other  prod- 
ucts which  may  render  the  nitroglycerine  unstable.  Hence  it 
is  necessary  to  keep  the  mixture  cool  while  the  conversion  is 
taking  place,  and  in  the  process  of  manufacture  this  is  effected 
in  various  ways.  Such  is  the  rationale  of  the  manufacture  of 
nitroglycerine  very  concisely  stated,  and  upon  it  the  various 
processes  are  based. 

Earlier  Laboratory  Experiments. — In  his  earlier  efforts  to 
make  nitroglycerine,  Sobrero,  the  discoverer  of  the  explo- 
sive, prepared  a  mixture  of  sulphuric  acid  (sp.  gr.  1.845)  an<3 
nitric  acid  (sp.  gr.  1.520)  in  the  proportions  of  2  parts  of 
the  former  to  one  part  of  the  latter,  and  allowed  it  to  cool, 
and,  during  the  process  of  nitration,  kept  the  temperature  of 
the  mixture  below  24°  C.,  by  external  cooling  with  ice.  Into 
this  mixture  he  introduced,  drop  by  drop,  with  constant 
agitation,  one-half  part,  by  volume,  of  anhydrous  glycerine. 
The  actual  amounts  used  in  these  experiments  were: 

H2SO4(sp.  gr.  1.845) 2.0  oz. 

HNO3(sp.  gr.  1.520) i.o  " 

C3H5(OH)3(anhyd.  puriss.) 0.5  " 

As  soon  as  the  conversion  was  complete,  the  entire  con- 
tents of  the  vessel  in  which  the  operation  was  conducted 
were  poured  slowly  into  a  vessel  containing  50  parts  (oz.)  of 
cold  water,  whereupon  the  nitroglycerine,  which  had  formed 
upon  the  surface  of  the  acid  mixture,  settled  to  the  bottom. 
The  supernatant  liquid  was  then  decanted,  and  the  nitro- 
glycerine freed  from  acid  by  thoroughly  washing  it  with  clear 
water. 

In  their  experiments  Praeger  and  Bertram  followed  the 
method  pursued  by  Sobrero  without  modification  so  far  as 
the  acid  mixture  was  concerned,  but  used  one  part  of  glycer- 
ine to  eight  parts  of  the  mixture,  instead  of  I  to  6.  Liebe, 
in  his  investigations,  duplicated  Sobrero's  method. 

De  Vrij  at  first  tried  nitric  acid  alone,  but  finally  adopted 
a  mixture  of  nitric  and  sulphuric  acids  in  varying  proportions, 
also  varying  the  amount  of  glycerine  from  one  part  to  six  or 
seven  parts  of  acids. 


270 


LECTURES   ON  EXPLOSIVES. 


Kopp  prepared  his  mixture  by  introducing  nitric  acid  in 
the  form  of  vapor  into  the  sulphuric  acid  which  had  been  pre- 
viously poured  into  the  receivers,  and  used  8  parts  of  mixed 
acids  to  one  part  of  glycerine.  In  addition  to  other  innova- 
tions in  the  process  of  manufacture,  Mowbray  prepared  his 
acid  mixture  by  introducing  sodium  nitrate  and  sulphuric  acid 
into  stills  and  absorbing  the  nitric  acid  vapor  by  sulphuric 
acid  contained  in  earthenware  receivers.  For  some  time  he 
retained  the  proportions  of  one  part  of  nitric  to  two  parts  of 
sulphuric  acid,  and  to  eight  and  one-half  parts  of  this  mix- 
ture he  added  one  part  of  glycerine. 

In  passing  from  the  experimental  stage  to  manufacturing 
nitroglycerine  upon  a  commercial  basis,  the  question  of  ex- 
pense became  almost  as  important  as  the  purity  of  the  final 
product,  and  in  many  cases  the  latter  factor  has  been  subor- 
dinated to  the  former,  oftentimes  at  the  cost  of  human  life. 

Proportions  of  the  Acid  Mixture. — As  in  the  manufacture 
of  guncotton,  so  in  making  nitroglycerine,  only  the  purest 
and  most  concentrated  acids  should  be  used  as  well  as  the 
purest,  and  most  anhydrous  glycerine. 

The  proportions  in  which  the  acids  are  mixed  and  the 
proportion  of  the  glycerine  to  the  acid  mixture  vary  with  the 
several  processes,  and  are  often  regulated  as  much  by  the 
relative  cost  of  material  as  upon  the  absolute  yield  of  explo- 
sive. The  proportions  most  universally  adopted  are  3  parts 
of  nitric  to  5  parts  of  sulphuric  acid,  and  to  8  parts  of  this 
mixture  from  i.o  to  1.15  parts  of  glycerine  are  added.  The 
exact  proportions  in  which  the  acids  are  mixed  to  each  100 
parts  of  glycerine  are  as  follows : 


HN03 

H,S04 

2lS 

584 

266 

cao 

Liebe        

2^8 

cS* 

De  Vrij  

COO 

070 

266 

caa 

28l 

«;67 

260 

52O 

Modern  Dynamite  ^^orks  

270—  "ZoO 

ACQ—  CQO 

NITRIC  ETHERS— NITROGLYCERINE.  2? I 

Process  of  Nitration. — On  account  of  the  amount  of  heat 
liberated  during  the  reaction  by  which  glycerine  is  converted 
into  nitroglycerine  it  is  not  practicable  to  introduce  all  of  the 
glycerine  into  the  acid  mixture  at  once  or  even  to  the  extent 
that  cotton  is  immersed  in  making  guncotton. 

Also,  on  account  of  the  viscosity  of  glycerine  which  pre- 
vents its  being  intimately  and  rapidly  mixed  with  the  acids, 
so  as  to  subject  every  particle  to  their  action,  it  is  necessary 
to  introduce  the  glycerine  very  gradually  and  with  constant 
agitation. 

Various  mechanical  devices  have  been  used  for  stirring 
the  glycerine  so  as  to  thoroughly  mix  it  with  the  acids,  but 
Dr.  Mowbray,  of  North  Adams,  Mass.,  appears  to  have  been 
the  first  to  suggest  the  use  of  compressed  air  for  that  purpose, 
although  Prof.  Barker  had  observed  about  the  same  time,  1868, 
that  by  introducing  a  current  of  air  into  the  nitrating  mixture 
not  only  were  the  materials  more  thoroughly  mixed,  but  that 
the  nitrous  vapors  were  partially  eliminated  and  the  mixture 
cooled,  thereby  rendering  possible  the  production  of  chemi- 
cally pure  nitroglycerine. 

The  use  of  compressed  air  in  mixing  the  acids  as  well  as 
in  the  converter  first  characterized  the  Mowbray  process  of 
making  nitroglycerine. 

The  same  method  was  used  in  Europe  by  Nobel,  and  was 
improved  by  Leidbeck,  who,  in  addition  to  mixing  the  glyc- 
erine with  the  acids  by  means  of  compressed  air,  introduced 
the  former  into  the  latter  in  the  form  of  a  shower  of  spray, 
with  the  result  that  the  operation  was  accelerated  and  the 
yield  of  nitroglycerine  increased. 

Manufacture  of  Nitroglycerine. — With  slight  modifica- 
tions the  method  of  making  nitroglycerine  commercially  may 
be  described  as  follows : 

The  plant  consists  of  acid  and  glycerine  tanks,  a  mixing 
apparatus  or  converter,  injectors,  separators,  washing  vats, 
filtering  apparatus,  storage  and  discharge  tanks,  and  a  denit- 
rification  apparatus. 

The  several  parts   of  apparatus  as   enumerated  are   con* 


272  LECTURES   ON  EXPLOSIVES. 

tained  in  wooden  building?,  made  as  lightly  as  is  consistent 
with  the  necessary  strength,  so  that  in  case  of  accident  the 
danger  from  flying  debris  may  be  reduced  to  a  minimum. 

Acid  Tank. — In  many  nitroglycerine  factories  the  acids 
are  purchased  already  mixed  in  the  proper  proportions,  being 
transported  in  large  cast-iron  drums  (capacity  1500  Ibs.)  made 
for  the  purpose,  so  that  when  about  ''to  make  a  run"  the 
proper  amount  of  mixed  acids  (which  are  already  cooled)  is 
introduced  into  the  acid  tank,  which  is  also  of  cast  iron,  and 
of  the  capacity  required  for  a  single  "  run"  of  nitroglycerine. 
This  tank  is  placed  upon  a  higher  level  than  the  converter, 
into  which  the  acids  are  introduced  by  merely  opening  a 
faucet.  In  factories  where  the  acids  are  made,  or  where  the 
acids  are  purchased  separately  and  then  mixed  so  as  to  insure 
the  proper  strength  and  purity,  the  acids  are  first  run  into  a 
large  cast-iron  mixing-tank  fitted  with  a  stirring-gear  (or  a  com- 
pressed-air apparatus),  thoroughly  mixed,  and  allowed  to  cool 
for  twelve  or  twenty-four  hours  before  being  transferred  to  the 
acid  tank.  The  use  of  lead-lined  tanks  is  being  gradually  dis- 
continued on  account  of  the  formation  of  lead  sulphate,  which 
interferes  with  the  separation  of  the  nitroglycerine  from  the 
waste  acids. 

Glycerine  Tank. — Upon  the  same  level  as  the  acid  tank, 
so  that  it  may  flow  easily  into  the  converter,  is  a  second  cast- 
iron  (or  wooden  lead-lined)  tank  of  smaller  dimensions,  into 
which  the  necessary  amount  of  glycerine  is  introduced  just 
previous  to  starting  the  process  of  nitration.  The  average 
amount  of  glycerine  used  in  a  ''single  run"  rarely  exceeds 
three  hundred  and  fifty  pounds,  the  amount  of  acids  required 
for  the  conversion  of  this  'amount  of  glycerine  into  nitroglyc- 
erine varying  according  to  the  table  already  given.  When 
not  forced  into  the  acid  mixture  in  the  converter  by  means  of 
compressed  air  through  injectors,  the  glycerine  is  led  into  the 
mixing  apparatus  by  a  tube  perforated  with  small  holes  so 
that  it  falls  upon  the  surface  of  the  acid  mixture  in  a  number 
of  fine  streams,  the  flow  being  regulated  by  a  tap. 

The  Converter. — This  consists   of   a  cast-iron  vessel,  sur- 


NITRIC  ETHERS— NITROGLYCERINE.  2?$ 

rounded  by  a  water-jacket,  and  contains  leaden  worms, 
through  which  water  continually  circulates  during  the  process 
of  nitration. 

Extending  through  the  centre  of  the  converter  is  a  shaft 
to  which  are  attached  blades  so  arranged  as  to  form  a  helical 
agitator  which  is  kept  constantly  revolving  during  the  process 
of  conversion.  The  end  of  this  shaft  extends  up  through  the 
top  of  the  converter,  which  is  also  perforated  to  receive  a  ther- 
mometer and  glass  tubes  through  which  the  nitrous  fumes 
escape.  The  top  is  also  often  fitted  with  glass  plates  to  en- 
able the  operator  to  watch  the  reaction  going  on  within  the 
apparatus.  At  the  bottom  is  a  large  discharge-tap,  by  means 
of  which  the  contents  of  the  converter  can  be  quickly  run  into 
the  discharge-tanks  in  case  of  danger,  or  into  the  separators 
when  the  nitration  is  complete. 

Injectors. — Instead  of  running  the  glycerine  into  the  con- 
verter by  pipes  as  just  described,  it  is  often  forced  into  the 
acids  by  means  of  injectors. 

The  injectors  are  so  arranged  that  the  glycerine  is  intro- 
duced into  the  acids  from  below,  and  in  the  form  of  spray. 
Two  objects  are  thereby  accomplished,  namely,  the  glycerine 
is  finely  divided  and  each  particle  is  immediately  subjected  to 
the  action  of  a  relatively  large  quantity  of  acids,  and  the  cold 
produced  by  the  expansion  of  the  compressed  air  serves  to 
reduce  the  temperature  during  the  reaction,  thereby  prevent- 
ing decomposition  by  local  heating,  as  often  occurs  when  the 
glycerine  is  introduced  from  above,  and  allowed  to  drop  upon 
the  surface  of  the  acid  mixture.  There  is,  however,  a  corre 
spending  disadvantage  attending  the  use  of  injectors  caused 
by  the  reduction  of  temperature  which  renders  the  glycerine 
viscous  and  difficult  to  force  through  the  injectors  in  very 
fine  spray. 

The  glycerine  should  not  be  introduced  into  the  acids 
until  the  temperature  of  the  latter  has  fallen  to  about  15°  C., 
and  during  the  process  of  nitration  the  flow  of  glycerine 
should  be  so  regulated  that  the  temperature  shall  not  exceed 
30°  C.  Although  decomposition  does  not  occur  below  50°  C., 


274  LECTURES   ON  EXPLOSIVES. 

it  is  possible  that  this  temperature  may  be  attained  in  certain 
portions  of  the  mixture  due  to  local  heating,  and  not  be  reg- 
istered by  the  thermometers. 

Once  this  point  is  reached,  it  readily  extends  throughout 
the  mass  and  is  very  difficult  to  regulate ;  hence  the  necessity 
of  watching  the  temperature  very  carefully  during  the  process 
of  nitration. 

Should  the  temperature  rise  to  30°  C.,  the  flow  of  glycer- 
ine should  be  reduced  or  entirely  shut  off,  and  the  agitation 
increased.  If  the  rise  of  temperature  still  increases,  and 
especially  if  the  partially  converted  charge  show  signs  of  ex- 
tensive *  'firing,"  the  discharge-faucet  at  the  bottom  of  the 
mixing  apparatus  should  be  opened  and  the  contents  emptied 
into  the  discharge-tanks  below,  all  hands  leaving  the  building 
as  rapidly  as  possible. 

The  process  of  nitration  may  be  summed  up  as  follows: 
The  mixed  acids  are  introduced  into  the  converter,  water 
made  to  circulate  through  the  water-jacket  and  cooling-worms, 
the  agitator  started,  and  the  glycerine-tap  opened:  The  ther- 
mometer is  now  closely  watched,  as  well  as  the  reaction 
through  the  glass  openings  in  the  top  of  the  converter,  and 
also  the  color  of  the  fumes  escaping  through  the  escape-pipes. 

Should  the  temperature  exceed  30°  C.  at  any  time,  or 
should  the  reaction  become  violent,  or  the  escaping  fumes  in- 
dicate "  firing,"  the  flow  of  glycerine  should  be  stopped  and 
the  agitation  and  circulation  of  the  water  increased.  If  in 
spite  of  these  precautions  the  "  firing"  continue  to  increase, 
the  discharge-tap  is  opened,  and  the  entire  contents  of  the 
converter  run  into  the  discharge-tank.  After  the  entire  charge 
of  glycerine  has  been  introduced  into  the  converter  the  water 
is  allowed  to  circulate  through  the  worms  for  a  few  moments 
and  the  agitation  continued  to  insure  thorough  nitration 
before  separating  the  nitroglycerine  from  the  acids. 

First  Separator. — Formerly  nitroglycerine  was  separated 
from  the  acids  by  skimming  it  from  the  surface  by  means 
of  wooden  scoops.  This  process  was  not  only  tedious  and 
wasteful,  but  dangerous,  and  is  no  longer  used.  A  simple 


NITRIC  ETHERS— NITROGLYCERINE.  2/5 

and  safe  way  of  separating  the  explosive  from  the  acids  is  to 
run  the  contents  of  the  mixing  apparatus  into  a  large  vessel 
of  water,  so  that,  the  acids  being  diluted  and  their  specific 
gravity  reduced,  the  nitroglycerine  settles  to  the  bottom  and 
the  supernatant  waste  acids  may  be  decanted  or  siphoned  off. 
This  method  is  expensive,  since  the  acids  are  entirely  lost,  and 
the  nitrous  fumes  produced  are  extremely  disagreeable  to  the 
workmen.  The  method  now  generally  adopted  in  the  large 
factories  is  known  as  the  direct  separation,  and  depends  upon 
the  difference  in  the  specific  gravities  of  the  waste  acids 
and  the  explosive.  The  specific  gravity  of  nitroglycerine 
being  about  1.60  and  that  of  the  waste  acids  1.70,  the  explo- 
sive when  formed  rises  to  and  remains  upon  the  surface  of  the 
mixture,  so  that  they  can  be  readily  separated. 

The  first  separator,  in  which  the  great  bulk  of  nitro- 
glycerine is  separated  from  the  acids  before  being  washed, 
consists  of  a  large  vessel  made  of  stout  sheet  lead,  having  a 
conical  or  pyramidal  bottom,  at  the  lowest  level  of  which  is 
fitted  a  separatory  funnel  connected  by  gutters  or  pipes  with 
the  discharge-tank  or  waste-acid  tank.  The  separator  is  closed 
with  a  wooden  lead-covered  or  cast-iron  top,  through  which 
pass  a  pipe  or  flue  for  conveying  away  the  nitrous  fumes,  and 
also  a  thermometer  for  registering  the  temperature  of  the  con- 
tents of  the  apparatus.  Through  the  side  of  the  separator,  at 
the  line  of  separation  of  the  nitroglycerine  and  waste  acids  (the 
same  charge  being  run  each  time),  extends  a  tap  by  means  of 
which  the  explosive  can  be  run  directly  into  the  first  washing 
vat  as  soon  as  the  separation  is  complete.  Since  excessive 
heating  is  liable  to  occur  in  the  separator,  it  is  usual  to  have  a 
stout  perforated  lead  pipe  fitted  in  the  lower  part  of  the  appa- 
ratus, through  which  in  case  of  necessity  compressed  air  may 
be  forced  to  agitate  the  mixture.  The  greater  part  of  the 
nitroglycerine  separates  from  the  acids  very  quickly  after  in- 
troduction into  the  separator,  and  when  anhydrous  glycerine 
and  concentrated  acids  are  used,  the  separation  should  be  com- 
plete from  one  half  to  three  quarters  of  an  hour.  When  sep- 
arated, the  side-tap  is  opened  and  the  nitroglycerine  is  run 


276  LECTURES   ON  EXPLOSIVES. 

directly  into  the  first  washing-vat,  and  the  waste  acids  are 
drawn  off  by  means  of  the  separatory  funnel  to  the  secondary 
separator,  while  such  nitroglycerine  as  did  not  pass  through  the 
side-tap  also  passes  through  the  separatory  funnel  after  the 
waste  acids  have  been  run  out  into  buckets  to  be  added  to  that 
already  in  the  washing-vat. 

First  Washing-vat. — The  next  operation  in  the  manu- 
facture of  nitroglycerine  is  freeing  the  explosive  from  acids, 
the  continued  presence  of  which  quickly  causes  decomposition. 
This  is  accomplished  by  continued  washing  in  a  large  volume 
of  water,  constantly  changing  the  wash-water,  and  from  time 
to  time  adding  sodium  carbonate  either  dry  or  in  the  form  of 
solution  to  neutralize  the  acid. 

The  first  washing  is  done  in  a  wooden  lead-lined  vat,  hav- 
ing an  inclined  bottom,  and  fitted  with  two  taps,  one  at  the 
lowest  level  of  the  bottom  which  discharges  into  a  pipe  or 
gutter  leading  to  the  second-washing  vat,  the  other  slightly 
above  the  level  of  the  nitroglycerine  in  the  vat  by  means  of 
which  the  wash-water  may  be  run  out  from  time  to  time  so 
that  fresh  water  may  be  introduced.  The  upper  tap  dis- 
charges into  a  pipe  or  gutter  which  carries  off  the  waste  water, 
which  in  this  country  is  thrown  away,  but  which  in  Europe 
is  subjected  to  secondary  treatment.  Through  the  bottom  of 
the  vat  passes  a  leaden  pipe  fitted  with  a  "  rosette  head,"  by 
means  of  which  compressed  air  is  introduced  so  as  to  agitate 
the  nitroglycerine  during  the  washing.  The  temperature  of 
the  water  should  be  kept  at  about  25°  C.,  varying  from  15°  C. 
at  the  beginning  of  the  operation  and  at  no  time  exceeding 
32°  C.  Instead  of  adding  sodium  carbonate,  it  is  better  to 
use  a  solution  of  soda,  and  then  only  after  the  wash-water  has 
been  changed  four  or  five  times,  so  as  to  avoid  the  violent 
reaction  due  to  the  evolution  of  carbonic  acid. 

The  use  of  an  excess  of  sodium  carbonate  is  to  be  avoided 
so  as  to  prevent  the  loss  of  nitroglycerine  due  to  its  decompo- 
sition by  that  substance.  The  washing  solution  should  not 
contain  more  than  2.50  per  cent  of  soda. 

Second  Washing-vat. — As  it  comes  from  the  first  wash- 


NITRIC  ETHERS— NITROGLYCERINE. 

ing-vat,  nitroglycerine  contains  many  impurities  from  which 
it  must  be  freed.  These  impurities  consist  of  traces  of  acids, 
secondary  products  of  nitration,  soda  mud,  etc.  Before 
filtration  the  explosive  is  therefore  subjected  to  a  final  wash- 
ing in  tepid  water  contained  in  wooden  lead-lined  vats. 
From  the  first  washing-vat  the  nitroglycerine  is  run  directly 
into  the  second  vat,  which  in  this  country  is  generally  fitted 
with  a  mechanical  stirrer  or  agitator,  and  thoroughly  washed, 
the  wash-water  being  changed  from  time  to  time  until  the 
explosive  will  stand  the  stability  test.  The  use  of  hot  water, 
while  it  accelerates  the  purification  of  the  explosive  by  vola- 
tilizing the  lower  nitrogen  oxides  present,  is  to  be  deprecated, 
since  even  at  50°  C.,  under  agitation,  nitroglycerine  is  slightly 
volatile,  so  that  there  is  an  appreciable  loss  in  the  yield. 

Filtering  Apparatus. — After  the  nitroglycerine  has  been 
washed  and  purified  so  as  to  be  able  to  stand  the  standard 
heat  test  before  being  stored,  it  is  further  freed  from  foreign 
particles  and  mechanical  impurities,  which  accumulate  during 
the  various  stages  of  manufacture  and  are  generally  held  in 
suspension  by  filtration.  The  apparatus  for  this  purpose 
consists  of  a  lead-lined  wooden  vat  fitted  with  an  inclined 
bottom,  at  the  lowest  level  of  which  is  a  tap  through  which 
the  nitroglycerine  may  be  drawn  off.  The  top  of  the  vat  is 
either  wholly  or  in  part  movable,  and  is  fitted  with  the  filter 
proper.  /The  filter  consists  of  a  copper  or  lead  cylinder  fitted 
with  lugs  on  the  outside  of  the  upper  and  on  the  inside  of  the 
lower  rim.  The  upper  lugs  prevent  the  cylinder  from  falling 
through  a  hole  in  the  top  of  the  vat  made  to  receive  it ;  the 
lower  lugs  hold  in  place  a  wire-gauze  disk  which  supports  the 
rest  of  the  filter.  Upon  the  wire  disk  is  placed  a  second 
disk  made  of  felt,  and  upon  the  latter  is  spread  evenly  and 
pressed  compactly  a  layer  of  common  salt  to  the  depth  of 
four  or  six  inches.  A  second  felt  disk  is  placed  over  the  salt 
and  is  held  in  place  by  a  second  wire-gauze  disk,  which  is 
secured  by  means  of  lugs  on  the  interior  of  the  cylinder  for 
that  purpose. 

For  the  removal  of  the  coarser  suspended  particles,  still 


LECTURES   ON  EXPLOSIVES. 

another  disk  of  very  fine  wire  gauze  is  sometimes  placed  within 
the  cylinder  and  about  twelve  inches  above  the  felt  salt-filter. 
From  time  to  time  it  is  necessary  to  remove  and  clean  the 
filter,  which  may  be  done  by  removing  the  cylinder  from  the 
vat,  releasing  the  upper  wire-gauze  and  felt  disks,  and  pour- 
ing the  salt  into  water  and  then  removing  the  lower  disks. 
The  salt  readily  dissolves,  and  any  nitroglycerine  held  by  it 
is  released,  settles  to  the  bottom,  and  may  be  recovered. 
The  disks  are  thoroughly  washed  in  warm  water,  and  the  filter 
is  ready  to  be  remounted  for  use,  replacing  the  old  salt  with 
a  fresh  layer.  Unless  the  nitroglycerine  is  to  be  used  in  the 
manufacture  of  explosive  gelatine  or  smokeless  powder,  it  is 
not  usual  to  filter  it. 

Storage -tanks. — Ordinarily  nitroglycerine  is  not  stored  in 
a  liquid  state,  the  size  of  the  run  being  limited  to  the  amount 
required  for  immediate  use  in  the  manufacture  of  dynamite  r 
so  that  the  explosive  is  run  directly  to  the  mixing-house,  to 
be  absorbed  by  the  dope,  which  converts  it  practically  from  a 
liquid  into  a  solid. 

When  not  immediately  used  in  this  way  it  is  stored  in 
lead-lined  wooden  tanks,  or  in  some  case,  as  in  smokeless- 
powder  works,  it  is  dissolved  in  the  proper  solvent  and  stored 
in  copper  vessels. 

Discharge-tanks. — These  tanks  have  been  mentioned  in 
connection  with  the  converter,  and  are  used  in  case  of  danger 
resulting  from  the  charge  "  firing  "  during  nitration.  They 
are  lead-lined  wooden  tanks  having  a  capacity  of  at  least 
twenty  times  that  of  the  converter.  Formerly  they  were 
placed  directly  beneath  the  converter,  but  on  account  of  the 
nitrous  fumes  developed  whenever  a  charge  is  "  drowned,"  it 
is  better  to  place  them  in  the  open  air  and  connect  them  with 
the  discharge-pipe  of  the  converter  by  means  of  a  gutter  or 
pipe.  The  discharge-tanks  are  kept  constantly  half  filled 
with  water,  which  should  be  changed  from  time  to  time,  even 
when  unused,  so  as  to  prevent  the  formation  of  organic  mat- 
ter. These  tanks  are  also  fitted  with  taps  at  the  bottom,  so 
that  the  water  or  drowned  charge  may  be  drawn  off;  and 


NITRIC  ETHERS— NITROGLYCERINE. 

whenever  such  a  charge  is  run  out,  care  should  be  taken  to 
collect  whatever  nitroglycerine  may  have  been  formed  in  the 
converter  before  the  discharge-tap  was  opened.  The  dis- 
charge-tanks are  also  connected  by  means  of  pipes  with  the 
separators,  for  the  same  reason  as  with  the  converter. 

Denitrification  Apparatus. — In  this  country  no  effort  is 
made  (at  least  at  the  nitroglycerine  works)  to  save  the  waste 
acids. 

Abroad,  however,  these  acids  are  treated,  and  the  use  of 
the  regained  acids  reduces  considerably  the  cost  of  the  manu- 
facture of  nitroglycerine.  The  waste  acids  are  introduced 
into  what  is  called  the  denitrification  apparatus,  which  con- 
sists of  a  lead  cylinder  lined  with  refractory  bricks,  set  with 
refractory  clay  and  tar*  The  cylinder  is  fitted  with  a  false 
bottom,  and  is  filled  with  broken  quartz.  A  large  earthen- 
ware pipe  at  the  top  serves  to  lead  the  nitrous  vapors  to  a 
cooling-worm,  where  they  are  condensed  and  collected  in 
large  Wolff  bottles.  Near  the  top  is  a  funnel  by  means  of 
which  the  acids  are  introduced  into  the  apparatus.  The 
quartz  is  heated  by  means  of  steam,  introduced  by  a  pipe 
which  enters  the  cylinder  on  a  level  with  the  false  bottom. 
A  second  pipe  below  this  bottom  serves  to  lead  the  denitri- 
fied sulphuric  acid  into  the  receiving-tanks. 

Process  Employed  by  the  French  Government  at  their 
Works  at  Vonges. — The  process  of  Boutmy  and  Faucher, 
which  is  employed  by  the  French  Government  at  their  works 
at  Vonges,  differs  in  principle  from  any  of  those  described. 
In  this  process  two  mixtures  are  first  prepared :  one  a  mix- 
ture of  nitric  and  sulphuric  acids  in  equal  proportions,  the 
other  a  mixture  of  one  part  of  glycerine  to  3.2  parts  of  sul- 
phuric acid.  These  are  thoroughly  cooled,  and  then  mixed 
together  in  the  proportion  of  5.6  parts  of  the  nitric-sulphuric 
mixture  to  4.2  parts  of  the  sulphoglycerine  mixture.  The 
whole  is  placed  in  an  earthen  pot,  surrounded  by  water,  and 
the  operation  is  left  to  take  place,  which  it  does  quietly,  the 
nitroglycerine  separating  as  formed  and  rising  to  the  surface 
of  the  liquid  mass,  from  which  it  is  eventually  skimmed  off, 


280  LECTURES   ON  EXPLOSIVES. 

washed,  and  purified.  The  theory  of  this  operation  is  that 
the  glycerine  and  sulphuric  acid  form  the  glycerol-sulphuric 
acid, 


CH 

l~>hl'     O.SO.H' 

and  that  this  reacts  with  the  nitric  acid  as  follows  : 

C,HS     (  +  3HN°'  =  C.H.O,(NO,).  +  2H.O  +  H,SO,. 


The  conversion  is  conducted  in  large  earthenware  crocks, 
which  are  placed  in  troughs  filled  with  cold  water.  The  two 
mixtures  are  prepared  in  the  following  quantities  : 

.  ,  (CSH6(OH)3.      10  kilogm. 
Sulphoglycenc  acid  ]     '     *        h  t* 

(  naow4  .....    $z 


XT.          ,....        .  ,     HNO3 28 

Nitrosulphunc  acid 


The  forty-two  kilogrammes  of  sulphoglyceric  acid  are 
divided  into  ten  equal  parts  and  introduced  into  ten  earthen- 
ware crocks,  and  the  nitrosulphuric  acid  is  similarly  and 
gradually  run  in  and  the  mixture  allowed  to  remain  overnight. 
It  is  claimed  that  the  heat  produced  by  the  Boutmy-Faucher 
process  serves  to  raise  the  temperature  during  conversion  to 
only  22°  C.,  whereas  the  temperature  during  the  reaction 
under  the  ordinary  process  rises  to  41°  C. 

It  is  also  claimed  for  this  process  that  it  is  simple  in  exe- 
cution, requires  but  little  apparatus,  is  safe,  and  gives  a  large 
yield.  The  claim  for  safety  is  questioned  on  the  ground  that 
the  nitroglycerine  remains  for  a  dangerously  long  time  in 
contact  with  the  acids,  and  the  explosion  at  Pembry  Burrows 
in  1883,  where  this  process  was  used,  is  cited  in  support  of 
this  criticism.  It  may  be  replied  that  it  is  now  the  custom 
at  the  factories  where  the  other  processes  are  employed  to 
allow  the  nitroglycerine  and  acids  to  remain  in  contact  for  a 


NITRIC  ETHERS— NITROGLYCERINE.  28 1 

long  time,  until  the  nitroglycerine  separates  completely  from 
the  acids,  so  that  by  skimming  the  acids  may  be  recovered 
undiluted,  and  that  the  operation  is  not  considered  extra 
hazardous ;  while,  besides,  Dr.  Dupre  found  that  very  impure 
glycerine  and  acid  had  been  used  at  Pembry  Burrows  at  the 
time  of  the  explosion,  and  this  was  sufficient  to  account  for 
its  origin. 

In  all  processes  for  making  nitroglycerine  the  greatest  care 
must  be  taken  to  prevent  any  accidental  mixture  of  water 
with  the  charge  in  the  converter.  A  very  little  water  shows 
itself  by  the  greater  trouble  and  slowness  in  running  and  in 
the  falling  off  of  the  product.  If  more  water  enters,  the  heat 
will  be  greater  than  can  be  carried  away  by  the  usual  means 
of  cooling,  and  the  charge  is  "fired."  Usually  this  means 
only  an  active  decomposition  accompanied  by  clouds  of  ni- 
trous vapors. 

Slight  fires  may  be  stopped  by  vigorous  agitation,  but  if 
the  firing  is  persistent  the  contents  of  the  tub  should  be  run 
off  as  rapidly  as  possible.  A  constant  agitation  of  the  liquid 
should  be  kept  up  during  drawing  off  to  prevent  separation  of 
the  nitroglycerine.  When  mixing  the  glycerine  in  the  con- 
verter the  operation  is  slowly  performed  in  order  to  keep  the 
temperature  down,  but  if  the  temperature  is  within  the  limit, 
the  mixing  should  be  performed  as  rapidly  as  possible  and  the 
nitroglycerine  removed  from  the  sphere  of  action.  Rapidity 
of  working  is  largely  dependent  upon  the  quality  of  acids 
used,  since  the  heat  evolved  is  least  when  the  strongest  acid 
is  used.  In  general,  with  highly  concentrated  acid  not  only 
is  the  product  proportionally  increased,  but  the  reaction  also 
goes  on  more  uniformly,  and  is  more  readily  controlled. 

The  Yield  of  Nitroglycerine  from  the  Various  Proc- 
esses.— From  the  equation  we  find  that  one  part  of  glycer- 
ine should  yield  2.46  parts  of  nitroglycerine,  but  this  is  never 
realized  in  practice.  The  proportion  of  nitroglycerine  ob- 
tained is  dependent  almost  entirely  upon  the  acid.  If  the 
glycerine  is  weak  the  product  will  fall  off,  but  the  small  dif- 
ference in  strength  of  glycerine  ordinarily  found  exercises 


282  LECTURES   ON  EXPLOSIVES. 

little  effect.  If  the  acids  are  weak,  however,  the  product  is 
markedly  less.  This  does  not  depend  to  any  extent  upon  the 
method  or  form  of  apparatus  employed,  but  only  upon  the 
acid  taken.  Weak  acids  will  carry  smaller  quantities  of 
glycerine  and  give  lower  proportional  products  than  strong 
ones;  consequently  statements  of  relative  products  obtained 
are  of  comparatively  little  value,  unless  accompanied  by  a 
statement  of  the  kind  of  acid  employed  and  the  relative 
amount  of  glycerine  treated.  At  Vonges  they  obtained  1.8, 
while  the  Ardeer  works  get  2  parts,  the  loss  being  accounted 
for  by  the  supposition  that  other  compounds  are  formed, 
which  are  carried  away  with  the  acids.  In  this  country  we 
obtain  rather  more  than  two  parts.  By  using  one  part  of 
glycerine  to  from  7.5  to  8  parts  of  mixed  acids  and  with  care 
in  the  preparation  of  materials  2.2  parts  can  be  obtained. 

Properties  of  Nitroglycerine. — At  ordinary  temperatures 
nitroglycerine  is  an  oily  liquid  having  a  specific  gravity  of  1.6. 
Freshly  made,  by  the  Mowbray  process,  it  is  creamy-white 
and  opaque;  but  becomes  transparent  ("clears")  and  color- 
less, or  nearly  so,  on  standing  for  a  time,  which  is  dependent 
on  the  temperature.  When  produced  by  "skimming"  it  is 
transparent,  but  it  is  often  found  in  commerce  to  have  a 
yellow  or  brownish-yellow  color. 

Although  very  slightly  soluble  in  it,  it  does  not  mix  with 
and  is  unaffected  by  cold  water.  It  has  a  sweet  pungent, 
aromatic  taste,  and  volatilizes  in  measurable  quantities  at 
50°  C. 

Nitroglycerine  is  soluble  in  methyl,  ethyl,  and  amyl  alco- 
hols ;  in  benzene ;  in  carbon  disulphide ;  in  all  proportions  in 
ether,  chloroform,  glacial  acetic  acid,  and  phenol;  and  spar- 
ingly in  glycerine. 

The  action  of  various  solvents  upon  nitroglycerine  has 
been  carefully  investigated  by  A.  H.  Elliot,  and  his  results 
are  summarized  as  follows : 


NITRIC  ETHERS— NITROGLYCERINE. 


283 


Solvent. 


Water 

Alcohol  :  Absolute 

93  per  cent 

80    "       "    

50    "      "      .... 

Methyl 

Amyl 

Ether:  Ethylic 

Acetic 

Chloroform 

Acetone 

Sulphuric  acid  (1.845) 

Nitric  "  (1.400) 

Hydrochloric  acid  (1.200). 

Acetic  acid,  glacial 

Carbolic  acid 

Astral  oil 

Olive  " 

Stearine  oil 

Mineral  jelly 

Glycerine  

Benzene 

Nitro-benzene 

Toluene  

Carbon  bisulphide 

Turpentine 

Petroleum  naphtha  (71°- 

76°  B.) 

Caustic  soda,  solution  1:10 
Borax,  solution  5  percent. 
Ammonium  hydrate (0.980) 
Ammonium  sulph-hydrate. 
Iron  sulphate,  solution  . . . 
"  chloride  (Fe  1.4  gm. 

to  10  c.c.  H2O) 

Tin  chloride 


Cold. 


insoluble 
soluble 

slowly  soluble 

insoluble 

soluble 


slowly  soluble 
insoluble — decomposed 
soluble 

insoluble 
soluble 

insoluble 
ii 

soluble 


insoluble 


;  S  separates 
slightly  affected 

slowly  affected 
slightly  affected, 


Warm. 


slightly  soluble 
soluble 


slightly  soluble 
soluble 


slowly  soluble 
soluble 

insoluble 
soluble 
it 

insoluble 
soluble 


slightly  affected 
soluble 

insoluble 


"        ;  slightly  affected 
decomposed 
affected 

decomposed 
affected 


Nitroglycerine  is  an  active  poison,  mere  contact  with  it 
producing  nausea,  giddiness,  faintness,  and  an  especially 
painful  form  of  headache  at  the  base  of  the  brain.  Either  in 
a  liquid  state  or  in  the  form  of  vapor  or  fumes,  it  readily 
attacks  the  glands  of  the  moist  membranes  of  the  nose  or 
mouth,  and  is  immediately  absorbed  with  the  effects  men- 
tioned. Persons  of  highly  nervous  temperament  are  par- 
ticularly sensitive  to  the  action  of  nitroglycerine,  and  never 
become  accustomed  to  it,  although  the  majority  of  workmen 
in  the  factories  are  quickly  inured.  Black  coffee  sometimes 
affords  relief,  but  the  usual  antidote  administered  by  phy- 


284  LECTURES   ON  EXPLOSIVES. 

sicians  is  the  Acetate  of  morphia.  In  many  cases  the  extract 
of  sarsaparilla  (Hood's)  affords  almost  instantaneous  relief. 

Nitroglycerine  is  rapidly  decomposed  by  alkaline  sulphides 
with  the  separation  of  sulphur,  and  slowly  decomposed  by  an 
alcoholic  solution  of  potassium  hydroxide,  by  ammonia,  alka- 
line carbonates,  hydrogen-sodium  phosphate,  hot  water,  fer- 
rous chloride,  hydrogen  chloride,  and  sulphuric  acid  (i:io), 
though,  according  to  Hay,  concentrated  sulphuric  acid  has 
no  action  upon  it.  Its  presence  may  be  detected  by  a  solu- 
tion of  aniline  in  concentrated  sulphuric  acid  which  yields  a 
purple  color  with  nitroglycerine,  that  changes  to  green  on  the 
addition  of  water. 

Freshly  made  opaque  nitroglycerine  freezes  at  from  —  19° 
to  —  22°  C.,  while  the  transparent  or  "  cleared  "  nitroglycer- 
ine freezes  at  from  3°  to  4°  C.,  in  both  cases  freezing  to  a 
white  crystalline  mass. 

Once  frozen  it  remains  in  this  condition,  even  when  ex- 
posed for  some  time  to  a  temperature  sensibly  above  its  freez- 
ing-point. 

In  a  frozen  state  nitroglycerine  is  less  sensitive  to  con- 
cussion than  when  liquid,  and  advantage  may  be  taken  of 
this  property  in  order  to  transport  the  explosive  with  com- 
parative safety. 

How  to  Thaw  Nitroglycerine  and  its  Compounds. — 
The  liability  of  nitroglycerine  to  freeze  presents  difficulties 
and  dangers  to  those  who  use  it  in  cold  climates,  since  when 
frozen  it  loses  a  great  deal  of  its  force  when  exploded,  and 
the  process  of  thawing  is  always  attended  with  danger  unless 
conducted  carefully.  The  best  way  to  thaw  nitroglycerine 
(and  nitroglycerine  powders)  is  to  place  the  vessels  containing 
the  explosive  in  a  room  heated  by  steam  and  to  so  regulate 
the  temperature  that  it  shall  not  exceed  50°  C. 

For  practical  use  in  the  field  and  in  mines  a  special  appa- 
ratus for  thawing  nitroglycerine  (and  its  compounds)  has 
been  devised,  and  is  generally  known  as  a  "jacketed  pot  " 
It  consists  essentially  of  two  water-tight  vessels  (tin  or 
copper),  one  considerably  smaller  than  the  other,  in  which  the 


NITRIC  ETHERS— NITROGLYCERINE.  28$ 

explosive  is  placed,  and  the  other  to  hold  water  heated  to  a 
temperature  not  exceeding  50°  C. 

The  smaller  vessel  containing  the  explosive  is  suspended 
in  the  water  contained  in  the  larger  or  outer  one  and  both 
are  covered  so  as  to  retain  the  heat.  The  water  is  changed 
from  time  to  time  as  it  cools  until  the  explosive  is  thawed. 
Under  no  circumstances  should  vessels  containing  nitro- 
glycerine be  placed  in  the  vicinity  of  a  hot  fire,  upon  heated 
steam  pipes,  near  steam-boilers,  or  upon  hot  bricks,  etc.,  nor 
should  the  explosive  be  placed  in  the  vessel  containing  the 
water.  Moreover,  the  outer  vessel  should  be  carefully  ex- 
amined before  use,  in  order  to  be  sure  that  no  nitroglycerine 
has  accidentally  found  its  way  therein. 

The  inconvenience  presented  by  frozen  nitroglycerine  and 
the  danger  attending  the  process  of  thawing  when  conducted 
by  ignorant  or  careless  workmen  has  led  to  efforts  to  obviate 
these  difficulties  by  lowering  the  freezing-point  of  the  ex- 
plosive. 

In  1885  Nobel  discovered  that  when  nitrobenzene  was 
added  to  nitroglycerine  the  freezing-point  of  the  explosive 
was  perceptibly  reduced.  Guttman  made  a  similar  observation 
about  the  same  time,  and  in  his  subsequent  experiments  found 
that  the  same  result  was  produced  by  other  benzene  and 
phenol  substances,  including  the  pyridine  bases  and  salts. 

Practically  these  discoveries  were  of  little  use,  since  by 
their  addition  the  freezing-point  was  very  slightly  reduced, 
while  the  addition  of  5  per  cent  of  nitrobenzene  sufficed  to 
render  it  very  difficult  to  explode  the  mixture,  and  at  the  same 
time  it  reduced  the  effect  one  quarter. 

Pure  nitroglycerine  is  not  sensitive  to  friction  or  moderate 
percussion,  except  when  pinched  between  metallic  surfaces. 
If  placed  upon  an  anvil  and  struck  with  a  hammer,  only  the 
particle  struck,  as  a  rule,  explodes,  scattering  the  remainder. 
A  quantity  of  it  has  been  thrown  up  by  means  of  a  rocket  to 
a  height  of  1000  feet,  from  which  it  fell  without  being  ex- 
ploded on  impact.  When,  however,  in  a  state  of  decomposi- 
tion, it  is  exceedingly  sensitive  and  explodes  violently  when 


286  LECTURES   ON  EXPLOSIVES. 

struck,  even  if  unconfined.  It  must  be  noted  that  if  com- 
pletely confined  the  effect  of  a  blow  on  pure  nitroglycerine 
may  produce  explosion,  since  from  its  liquid  form  it  is 
nearly  incompressible.  In  the  case  cited  above  local  explo- 
sion occurs  only  because  the  hammer  is  lifted,  and  the  rest  of 
the  explosive  is  blown  away ;  but  if  it  was  so  confined  that 
there  was  no  escape  for  the  effect  of  the  explosion  of  the  par- 
ticle first  struck,  the  whole  mass  would  probably  be  fired.  If 
nitroglycerine  is  freely  exposed  to  flame  it  burns  with  a  bril- 
liant flame  and  without  explosion.  If  a  drop  of  nitroglycerine 
be  placed  on  a  metal  plate  and  slowly  heated  up,  the  nitro- 
glycerine may  be  completely  vaporized  without  explosion,  or 
if  the  plate  be  first  heated  to  incandescence  and  the  drop  then 
placed  upon  it,  the  drop  will  assume  the  spheroidal  condition 
and  eventually  volatilize  without  explosion,  but  if  the  hot 
plate  be  just  below  incandescence,  so  that  the  nitroglycerine 
can  come  in  contact  with  it,  the  drop  explodes  with  a  violent 
report.  The  firing-point  of  nitroglycerine  is  about  180°  C. 
(356°  F.),  but  it  begins  to  decompose  under  the  influence  of 
heat  at  a  somewhat  lower  temperature. 

According  to  the  investigations  of  Leygue  and  Champion, 
nitroglycerine  behaves  very  eccentrically  at  different  temper- 
atures : 

At  185°  C.  it  boils,  evolving  nitrous  fumes; 

194°        it  volatilizes  slowly; 

200°        it  evaporates  rapidly  ; 

217°        it  detonates  violently ; 

241°        it  merely  explodes; 

257°        it  explodes  violently ; 

267°        it  explodes  with  less  violence  than  at  257° ; 

287°        it  explodes  as  at  241°. 

By  subjecting  nitroglycerine  to  a  continuous  temperature 
of  70°  C.  it  may  be  completely  evaporated  (Hess).  Such 
experiments  as  those  conducted  by  Leygue  and  Champion, 
Hess,  Kopp,  and  others  are  limited  to  very  minute  quantities 
of  the  explosive,  since  to  heat  larger  masses  above  180°  C. 
is  almost  invariably  followed  by  an  explosion. 


NITRIC  ETHERS— NITROGLYCERINE.  28/ 

How  to  Fire  Nitroglycerine. — In  order  to  fire  nitro- 
glycerine so  as  to  develop  its  maximum  explosive  effect  it  is 
necessary  to  use  blasting-caps,  or  detonators,  containing  mer- 
cury fulminate,  it  being  more  sensitive  and  responding  more 
readily  to  the  initial  action  of  the  fulminate  than  guncotton. 

For  success,  it  is  also  essential  that  the  detonator  should 
be  immersed  in  the  liquid  so  as  to  be  in  direct  contact  with 
it,  but  when  the  caps  are  fired  by  means  of  a  running  fuse 
care  should  be  taken  that  the  fuse  does  not  touch  the  nitro- 
glycerine, as  the  latter  may  be  set  on  fire  before  the  cap 
explodes,  and  an  incomplete  explosion,  which  would  produce 
poisonous  fumes  and  cause  a  loss  of  energy,  might  then  result. 
When  fired  by  a  gunpowder  fuse  only,  the  action  is  very 
uncertain,  for  sometimes  the  nitroglycerine  is  exploded 
and  sometimes  not,  and  even  when  exploded  by  this  means 
the  force  developed  is  much  less  than  when  it  is  detonated 
by  means  of  a  fulminate.  It  may  be  detonated,  even  when 
frozen,  by  means  of  a  heavy  charge  of  fulminate,  but  the 
action  is  not  certain.  Its  insensitiveness  when  in  the  frozen 
condition  is  shown  by  the  fact  that  1600  pounds  of  the  liquid 
exploded  in  a  magazine  which  contained  also  600  pounds  of 
the  frozen,  and  that  the  latter  was  broken  up  and  scattered  in 
every  direction  without  being  exploded. 

Decomposition  of  Nitroglycerine. — The  idea  that  nitro- 
glycerine, even  when  pure,  spontaneously  decomposes  at  ordi- 
nary temperatures  after  lapse  of  time  is  no  longer  entertained, 
but  on  the  contrary  nitroglycerine  has  been  stored  in  large 
quantities  for  years  without  any  special  precaution  having 
been  taken  to  protect  it,  and  without  the  appearance  of  any 
trace  of  decomposition.  Like  guncotton,  however,  nitroglycer- 
ine is  very  susceptible  to  heat,  and  even  when  thoroughly  puri- 
fied it  will  not '  stand  a  temperature  of  100°  C.  for  a  longer 
period  than  a  few  hours  without  undergoing  decomposition. 
Up  to  45°  C.  nitroglycerine  properly  made  and  purified  re- 
mains unchanged  almost  indefinitely,  but  beyond  that  degree 
of  temperature  its  stability  becomes  affected  within  a  few 
weeks. 


288  LECTURES   ON  EXPLOSIVES. 

The  action  of  the  direct  rays  of  sunlight  is  known  to  cause 
the  decomposition  of  nitroglycerine  as  well  as  the  presence 
of  free  acid  and  lower  nitric  compounds.  According  to  Brull, 
when,  owing  to  the  presence  of  free  acid,  decomposition  sets 
in,  it  proceeds  in  a  slow  and  tranquil  manner,  disengaging 
nitrous  vapors,  which  color  the  liquid  green,  then  developing 
nitrogen  and  carbon  dioxide  and  crystals  of  oxalic  acid,  until 
after  some  months  the  entire  mass  is  converted  into  a  green- 
ish gelatinous  body  composed  of  oxalic  acid,  water,  and 
ammonia.  Sometimes,  if  the  temperature  is  high,  as  when 
heated  by  the  sun,  the  decomposition  is  more  active,  but  it 
by  no  means  always  leads  to  an  explosion,  though  this  must 
depend  somewhat  upon  the  quantity  involved. 

With  ordinary  care  and  the  most  common-sense  precau- 
tions serious  accidents  resulting  from  the  decomposition  of 
large  quantities  of  nitroglycerine  may  be  prevented.  As 
just  stated,  the  primary  cause  of  decomposition  is  the  pres- 
ence of  free  acid,  which  may  be  easily  detected  by  the  most 
ignorant  person.  Nitroglycerine  may  be  conveniently  stored 
in  large  earthenware  crocks,  which  should  be  placed  in  copper 
buckets  to  catch  any  of  the  explosive  which  might  by  any 
chance  escape  from  the  crocks.  When  thus  stored,  the  nitro- 
glycerine should  be  covered  with  a  layer  of  water,  and  by 
testing  this  water  from  time  to  time  with  litmus  paper  the 
least  development  of  acidity  in  the  explosive  is  made  known. 

Should  the  nitroglycerine  be  stored  in  tin  cans,  by  remov- 
ing the  caps  and  suspending  the  litmus  paper  immediately 
over  the  opening  any  traces  of  acidity  are  at  once  discovered. 
In  any  case,  by  hanging  strips  of  litmus  paper  around  the  in- 
terior of  the  magazine,  and  examining  them  from  time  to 
time,  a  very  approximate  idea  of  the  condition  of  the  nitro- 
glycerine can  be  formed.  Should  any  slight  acidity  be  devel- 
oped and  the  means  be  at  hand,  the  nitroglycerine  should  be 
thoroughly  washed  as  already  described.  Should  the  litmus 
paper  show  strong  acid  reaction,  and  especially  if  any  green 
color  be  developed  in  the  explosive,  it  should  be  destroyed  at 


NITRIC  ETHERS— NITROGLYCERINE.  289 

once,  the  best  way  of  doing  this  being  to  explode  it  in  a  safe 
place. 

One  very  frequent  source  of  accidental  explosion  results 
from  gross  carelessness  in  allowing  cans  or  other  vessels  in 
which  nitroglycerine  has  been  stored  to  lie  around  loosely. 
In  nearly  every  case  particles  of  the  explosive  adhere  to  the 
vessels,  and  oftentimes  the  verdict  of  "  accidental  death" 
should  read  "  deliberate  suicide."  All  such  vessels  should  be 
destroyed  immediately. 

The  Use  of  Nitroglycerine  in  Blasting. — In  spite  of 
the  many  accidents  that  have  occurred  with  it,  nitroglycerine 
has  been  found  to  be  so  valuable  that  its  use  has  steadily  and 
largely  increased.  In  difficult  blasting,  where  very  violent 
effects  are  required,  it  surpasses  all  others.  Its  liquid  form  is 
a  disadvantage,  except  under  favorable  circumstances,  such  as 
when  at  'he  place  where  it  is  to  be  employed.  It,  however, 
forms  the  essential  ingredient  in  a  number  of  solid  mixtures, 
which  will  be  considered  later.  When  used  in  blasting  or 
similar  work  it  is  usually  put  in  tin  cans  or  cartridge-cases.  A 
very  good  case  may  be  made  for  it  by  rolling  up  stout  brown 
paper  into  a  cylinder  of  the  desired  diameter,  gluing  it,  and 
fastening  a  cork  into  one  end  by  choking  with  fine  wire. 
When  dry  the  case  is  soaked  in  melted  paraffin.  The  fuse 
wires  should  pass  snugly  through  a  cork  which  fits  the  open 
end.  This  cork  may  be  firmly  fixed  in  the  case  by  means  of 
small  tacks.  If  the  bore-holes  are  water-tight  it  may  be 
poured  directly  into  them,  but  it  is  rarely  safe  to  do  this,  as 
there  is  great  danger  that  some  of  it  will  escape  through 
seams  in  the  rock  and  not  be  exploded,  remaining  to  cause 
accident  at  a  future  time.  Since  nitroglycerine  is  so  readily 
detonated  it  has  the  advantage  of  not  requiring  strong  con- 
finement. Even  when  freely  exposed  it  will  exert  violent 
effects  such  as  breaking  masses  of  rocks  or  blocks  of  iron. 
So  in  blasting  it  requires  but  little  tamping.  Loose  sand 
or  water  is  entirely  sufficient.  The  relative  force  of  nitro- 
glycerine is  not  easily  estimated,  since  the  effect  produced 
depends  greatly  on  the  attendant  circumstances.  Thus,  a 


2gO  LECTURES   ON  EXPLOSIVES. 

charge  of  nitroglycerine  in  wet  sand  or  any  soft  material  will 
exercise  but  a  slight  effect,  while  the  same  charge  will  shatter 
many  tons  of  the  hardest  rock.  In  the  former  case  much 
more  sand  would  be  thrown  out  by  a  slower  explosion,  which 
would  gradually  move  it,  than  by  the  sudden  violent  shock 
of  the  nitroglycerine,  which  would  only  compress  the  material 
immediately  about  it.  But  in  the  hard  rock  the  sudden  ex- 
plosion is  much  more  effective  than  the  same  amount  of  force 
more  slowly  applied. 

Nitroglycerine  is  now  but  little  used  in  the  free  state,  its 
principal  use  in  this  condition  being  for  "  shooting"  oil-wells, 
in  order  to  free  them  from  the  paraffins  with  which  they  be- 
come clogged,  or  to  shake  the  oil-bearing  sandstones  so  as  to 
increase  the  yield.  The  torpedoes  used  for  this  purpose  con- 
sist of  tin  shells  from  three  to  five  inches  in  diameter,  and 
from  five  to  twenty  feet  in  length.  These  shells  are  taken 
to  the  well  empty,  the  longer  ones  being  in  sections  which 
are  put  together  as  they  are  inserted  in  the  well.  After  the 
shells  are  inserted  they  are  filled  with  the  explosive,  closed 
with  a  tightly-fitting  cover  to  which  a  strong  percussion-cap 
is  attached,  and  lowered  to  the  bottom  of  the  well  (which  is 
often  1500  feet  or  more  in  depth)  by  means  of  a  wire.  A 
perforated  iron  weight  is  then  strung  on  the  wire,  and  when 
the  torpedo  is  in  place  it  is  exploded  by  allowing  the  iron 
weight  to  drop  from  the  surface  and  strike  upon  the  cap.  An 
advantage  which  nitroglycerine  possesses  over  gunpowder  for 
use  in  mining  is  that  in  the  liquid  state  it  may  be  poured 
directly  into  the  bore-hole,  and  that  it  may  readily  and  easily 
be  tamped  by  pouring  water  upon  it,  thus  avoiding  the  dan- 
gerous process  of  tamping  by  ramming,  which  has  given  rise 
to  many  accidents  and  caused  the  loss  of  many  lives.  It  is 
obvious,  however,  that  liquid  nitroglycerine  can  be  used  for 
this  purpose  only  in  holes  which  tend  downwards,  while  in  the 
operation  of  mining  it  is  necessary  to  drive  holes  in  every  di- 
rection. This,  together  with  the  fact  already  noticed  that  the 
liquid  state  made  nitroglycerine  a  difficult  substance  to  store, 
transport,  and  use  with  safety,  impressed  the  manufacturers 


NITRIC  ETHERS— NITROGLYCERINE.  29! 

with  the  necessity  for  devising  some  means  by  which  it  could 
be  converted  into  such  a  solid  state  that  the  dangers  noted 
could  be  avoided,  while  its  great  power  and  susceptibility  to 
detonation  could  still  be  used  at  will.  How  this  has  been 
accomplished  will  be  shown  in  the  next  lecture.  It  should  be 
noted  here,  however,  that  a  device  employed  by  Nobel  to 
render  nitroglycerine  insensitive  until  desired  for  use  was  by 
adding  15  to  20  per  cent  of  methyl  alcohol  to  it.  The  two 
liquids  were  perfectly  miscible,  and  the  mixture  was  com- 
pletely insensible  to  blows  and  even  to  detonation.  When 
desired  for  use  6  to  8  volumes  of  water  were  added,  which 
precipitated  the  nitroglycerine  out  unchanged.  It  can  readily 
be  seen,  however,  that  this  scheme  was  commercially  imprac- 
ticable. 

Tests  for  Nitroglycerine. — It  is  sometimes  desirable  to 
ascertain  if  a  substance  contains  nitroglycerine,  without  under- 
taking a  complete  analysis.  Under  such  circumstances  the 
following  simple  tests  may  be  applied : 

If  a  liquid  is  oozing  from  a  substance,  or  can  be  squeezed 
from  it,  put  a  drop  of  it  on  blotting-paper.  If  it  is  nitro- 
glycerine it  will  make  a  greasy  spot,  which  will  not  disappear 
nor  dry  away  upon  standing;  struck  with  a  hammer  upon 
iron,  it  explodes  with  a  sharp  report;  lighted,  it  burns  with  a 
yellowish  to  greenish  flame,  emitting  a  crackling  sound ;  and 
placed  upon  an  iron  plate  and  heated  from  beneath,  it  ex- 
plodes sharply. 

Again,  introduce  a  few  drops  into  a  test-tube,  and  shake 
it  up  with  a  little  methyl  alcohol  which  has  been  previously 
tested  (by  pouring  a  little  of  it  into  distilled  water  and  seeing 
that  it  produces  no  turbidity).  After  shaking,  filter  the  con- 
tents of  the  tube  into  a  second  test-tube,  and  add  a  little 
distilled  water  to  the  latter.  If  the  nitroglycerine  is  present 
the  liquid  will  become  milky,  and  the  nitroglycerine  will 
eventually  separate  and  collect  at  the  bottom  of  the  tube  as  a 
heavy  lustrous  liquid.  A  much  more  delicate  test  is  with  a 
solution  of  aniline  and  concentrated  sulphuric  acid  as  follows0. 


292  LECTURES   ON  EXPLOSIVES. 

Aniline    I  volume 

HaS04(i.S4) 40       « 

'Proceed  as  in  the  test  just  described  with  methyl  alcohol,  but 
before  adding  the  water  introduce  into  the  tube  a  few  drops 
of  the  aniline  solution,  which,  if  nitroglycerine  be  present, 
will  produce  a  deep-purple  color.  The  color  thus  produced 
changes  to  green  upon  the  addition  of  distilled  water. 

The  tests  for  the  condition  of  nitroglycerine  as  to  stability, 
etc.,  do  not  differ  materially  from  those  described  for  guncot- 
ton. 

Test  for  the  Presence  of  Free  Acid. — Put  2.5  grammes 
in  a  thoroughly  cleaned  and  dried  test-tube,  and  add  10-20 
c.c.  of  distilled  water.  Cork  with  a  clean  cork,  and  shake  the 
tube  vigorously  for  two  or  three  minutes,  and  allow  it  to 
stand  for  a  minute  or  two.  Decant  the  supernatant  liquid 
into  a  second  tube,  which  has  been  previously  thoroughly 
cleaned,  and  test  it  with  litmus  paper,  or,  better,  with  methyl- 
orange. 

Stability  or  Heat  Test  for  Nitroglycerine. — Precisely 
the  same  apparatus  and  methods  are  used  as  in  the  case  of 
guncotton,  with  the  following  modifications:  Five  (5)  grains 
of  the  explosive  are  used  instead  of  twenty,  and  the  time 
allowed  for  the  appearance  of  the  color  on  the  test-paper  is 
reduced  from  fifteen  (15)  to  ten  (10)  minutes.  Great  care 
must  be  taken  in  introducing  the  nitroglycerine  into  the  tube 
so  that  the  sides  of  the  tube  may  not  be  soiled. 

Nitrogen  Test. — In  order  to  determine  the  exact  per- 
centage of  nitrogen  in  nitroglycerine,  it  is  necessary  that  the 
sample  introduced  into  the  nitrometer  shall  be  perfectly  an- 
hydrous. A  weighed  quantity  of  the  explosive  is  therefore 
exposed  in  a  desiccator  until  Constant  weight  is  obtained. 
The  thoroughly  dried  sample  is  then  introduced  into  the 
nitrometer,  and  the  test  is  performed  in  the  same  manner  as 
already  described  in  the  case  of  guncotton.  Nitroglycerine 
having  the  formula  C8H6O8(NO2)8 ,  the  percentage  of  nitrogen 
should  be  18.50.  The  ultimate  analysis  of  compounds  con- 
taining nitroglycerine  will  be  considered  subsequently. 


NITRIC  ETHERS— NITROGLYCERINE.  293 

The  Explosive  Effect  of  Nitroglycerine. — From  the 
properties  of  nitroglycerine  as  enumerated  above,  and  the 
numerous  methods  by  which  the  explosive  reaction  resulting 
in  the  decomposition  of  the  explosive  may  be  provoked,  it  is 
evident  that  the  resulting  explosive  effect  may  be  made  to 
vary  between  very  wide  limits.  Once  started,  however,  the 
initiatory  step  has  no  influence  upon  the  nature  of  the  prod- 
ucts of  the  reaction,  which  is  generally  expressed  by  the  fol- 
lowing equation : 

2C3HB08(N02)3  =  6CO,  +  5HaO  +  6N  +  O. 

According  to  this  equation,  we  note  that  nitroglycerine 
possesses  another  very  exceptional  property  (not  previously 
mentioned)  in  that  it  contains  in  itself  more  oxygen  than  is 
required  for  the  complete  combustion  of  its  elements,  the 
percentage  composition  of  the  gaseous  products  being 

CO, 58.20  per  cent 

HaO 19.80    "      " 

N 18.50    "      " 

O 3.50    "      « 


IOO.OO 

If  we  suppose  that  the  substance  be  converted  entirely 
into  gas,  it  will  have  a  constant  volume  of  22.32  litres  at  o°  C. 
and  76  cm.,  and  a  very  simple  calculation,  based  upon  the 
above  reaction,  will  show  that  227  grammes  of  nitroglycerine 
yield  161.82  litres  of  gas  under  these  conditions. 

If,  however,  instead  of  aqueous  vapor  the  water  be 
liquid,  the  volume  of  permanent  gas  for  a  single  equivalent 
of  the  explosive  amounts  to  106  litres,  or  for  one  kgm.  467 
litres. 

Berthelot  further  calculates  the  heat  of  total  combustion, 
which  in  this  case  is  identical  with  the  heat  of  decomposition 
as  follows :  The  water  being  liquid,  the  heat  developed  will 
be  at  constant  pressure  +  356.5  cal., 

at  constant  volume    -f-  358.5  cal., 


294  LECTURES   ON  EXPLOSIVES. 

The  water  being  gaseous,  the  heat  developed  will  be 
at  constant  pressure  -f-  331.1  cal., 
at  constant  volume    +  335-6  cal. 

Or,  for  one  kgm.,  the  water  being  liquid,  the  heat  developed 
will  be      at  constant  pressure  +  1S7°  ca^> 
at  constant  volume    +1579  cal. 

In  their  investigations  Sarrau  and  Vieille  found  the  heat 
developed  to  be  -f-  1600  cal. 

The  theoretical  temperature  may  be  calculated  at  constant 
pressure  or  constant  volume,  the  result  depending  upon  which 
of  the  above  values  be  used. 

Thus  at  constant  volume  we  have 


Substituting  this  value,  we  find  that  each  equivalent  of 
nitroglycerine  produces  33  14  litres  of  permanent  gas,  which 
at  constant  volume  exerts  a  pressure  of  23,360  atmospheres. 


LECTURE    XV. 

GUNCOTTON    BLASTING-POWDERS   AND    DYNAMITES. 

IF  we  refer  to  the  equation  assumed  to  represent  the 
reaction  which  occurred  when  the  cellulose  nitrate  used  by 
Karolyi  in  his  experiments  was  exploded,  or  to  the  formula 
adopted  by  Vieille,  we  see  that  the  products  of  explosion  are 
those  of  incomplete  combustion.  The  importance  of  this  fact 
was  quickly  appreciated,  and  almost  immediately  suggested 
the  practicability  of  devising  an  explosive  which  should  be 
essentially  guncotton,  but  in  which  the  deficiency  in  oxygen 
should  be  supplied  by  the  addition  of  oxidizing  agents  so  as 
to  obtain  more  complete  combustion. 

Several  such  mixtures  have  been  prepared  and  have 
proved  successful.  In  some  cases  it  has  been  found  desirable 
to  produce  the  explosive  in  a  granular  or  some  regular  form, 
and  cementing  agents,  such  as  gum,  resin,  paraffin,  etc.,  have 
been  added  for  this  purpose;  but  such  extraneous  matter 
must  be  considered  in  the  nature  of  an  adulterant  ratty^r 
than  as  adding  anything  to  the  strength  or  explosive  force  of 
the  mixture. 

Various  nitrates,  such  as  sodium,  potassium,  ammonium, 
and  barium,  have  been  added  to  guncotton  as  oxidizers,  with 
the  result  that  upon  explosion  all  of  the  poisonous  carbonic 
oxide  gas,  or  at  least  the  greater  part  of  it,  is  eliminated  by 
being  converted  into  carbonic  acid  gas.  The  additional 
claim,  however,  that  a  more  powerful  explosive  results  from 
the  admixture  of  nitrates  with  guncotton  is  doubtful. 

295 


296  LECTURES   ON  EXPLOSIVES. 

Tonite,  or  Tonite  Powder — This  explosive  was  intro- 
duced into  the  United  States  in  1881,  and  has  since  that  time 
been  manufactured  in  large  quantities  under  an  English 
patent  by  the  Tonite  Powder  Company  of  San  Francisco.  It 
consists  of  a  mixture  of  pulverulent  guncotton  and  barium 
nitrate,  which  theoretically  should  bear  the  relation  of  60.28 
parts  of  the  former  to  39.72  parts  of  the  latter.  Practically, 
standard  tonite  consists  of 

Guncotton 52.5  parts. 

Barium  nitrate 47. 5      ' ' 

The  finely  divided  guncotton  and  nitrate  are  thoroughly 
moistened,  and  then  ground  and  intimately  incorporated 
under  edge  rollers  until  the  whole  becomes  an  uniform  paste. 
The  paste  is  then  formed  into  cartridges,  which  are  covered 
with  paraffined  paper. 

Tonite  is  whitish  in  appearance,  very  dense,  burns  slowly 
and  without  danger;  it  does  not  appear  to  be  sensitive  to 
shock  or  friction,  nor  does  it  explode  upon  the  impact  of  the 
service  bullet.  It  requires  an  unusually  strong  detonator  to 
cause  an  explosion,  the  full  effect  being  developed  by  a  special 
detonator  made  by  the  company,  known  as  the  "  Tonite 
Cap."  In  several  experiments,  in  which  ordinary  blasting- 
caps  (triple  and  quintuple  force)  were  used,  while  no  explosion 
occurred,  the  cartridge  ignited  and  burned  fiercely  in  the 
bore-hole  until  entirely  consumed. 

In  storage,  tonite  seems  to  resist  to  a  remarkable  degree 
the  extremes  of  climate.  In  strength  it  stands  to  the  gun- 
cotton  from  which  it  was  made  as  82  to  100. 

In  addition  to  tonite  as  described  above,  and  which  is  now 
known  as  Cotton  Powder  No.  I,  there  have  been  recently 
patented  two  other  varieties,  called  Cotton  Powder  No.  2  and 
No.  3,  the  former  consisting  of  "  guncotton  thoroughly  puri- 
fied, mixed  or  impregnated  with  a  nitrate  or  nitrates  and 
charcoal,"  the  latter  of  a  "  mixture  of  thoroughly  purified 
meta-di-nitrobenzol  and  thoroughly  purified  guncotton, 
mixed  or  incorporated  with  one  or  more  of  the  following 


GUNCOTTON  BLASTING-POWDERS  AND    DYNAMITES.    297 

ingredients,  namely,  nitrate  of  potassium,  nitrate  of  sodium, 
nitrate  of  barium,  and  chalk." 

Potentite.  —  This  is  a  "  nitrated  guncotton,"  identical 
with  tonite,  except  that  potassium  nitrate  is  substituted  for 
the  barium  salt.  If  we  assume  the  following  reaction  to 
represent  what  occurs  when  such  a  mixture  is  exploded,  viz.  : 


4(C6H703)03(N02)3 

+  i  SCO,  +  i4H  O  +  QN,  +  3K3CO, 


then  the  theoretical  composition  of  potentite  should  be 

Guncutton  .........  *  ........  66.20  parts. 

Potassium  nitrate  _____  .......  33-8o     " 

Jn  practice,  however,  these"  proportions  are  changed  some- 
what, the  amount  of  guncotton  required  by  theory  being 
reduced  about  20  per  cent. 

The  process  of  manufacture  and  properties  of  potentite 
are  almost  identical  with  those  of  tonite. 

Abel's  Guncotton  Powder  was  patented  in  1867,  and 
•consists  of  guncotton  mixed  with  a  large  proportion  of  an 
oxidizing  body,  such  as  potassium  chlorate  or  nitrate,  or 
sodium  nitrate,  or  mixtures  thereof,  with  an  addition  of  a 
small  proportion  of  alkali,  or  of  an  alkaline  carbonate.  The 
patentee  recommended  the  following  proportions: 

Guncotton  ........  ..........  70  to  40  parts. 

Oxidizing  substances   .......  29  to  59     " 

Alkaline  substances  ..........  I      " 

Bantock's  guncotton  powder  is  essentially  the  same  as  that 
just  described,  with  the  addition  of  a  neutral  salt. 

Dynamite.  —  On  account  of  the  many  disadvantages  attend- 
ing the  handling,  storage,  and  transportation  of  liquid  nitro- 
glycerine, efforts  were  made  soon  after  the  discovery  of  this 
•explosive,  in  which  it  was  sought  to  neutralize  these  dangers. 
In  1866  Nobel  perfected  his  invention,  and  in  the  following 
year  dynamite  appeared  for  the  first  time  in  a  commercial 
form.  In  the  English  patent  the  inventor  describes  his  new 


LECTURES   ON  EXPLOSIVES. 

production  as  follows:  *'  This  invention  relates  to  the  use  of 
nitroglycerine  in  an  altered  condition,  which  renders  it  far 
more  practical  and  safe  for  use.  This  altered  condition  of 
the  nitroglycerine  is  effected  by  causing  it  to  be  absorbed  in 
porous  inexplosive  substances,  such  as  charcoal,  silica,  paper, 
or  similar  materials,  whereby  it  is  converted  into  a  powder, 
which  I  call  dynamite,  or  Nobel's  Safety  Powder."  By  the 
absorption  of  the  nitroglycerine  in  some  porous  substance  it 
acquires  the  property  of  being  in  a  high  degree  insensible  to 
shocks,  and  it  can  also  be  burned  over  fire  without  exploding. 
It  is  evident  that  in  thus  absorbing  the  nitroglycerine  in  a 
solid  material  the  explosive  is  not  converted  into  a  solid,  but 
is  merely  retained  in  the  pores  of  the  absorbent  through  the 
force  of  capillarity. 

The  commercial  success  attending  the  invention  of  Nobel 
naturally  led  others  to  follow  where  he  had  led  and  to  examine 
the  suitability  of  various  materials  as  absorbents,  and  within 
an  incredibly  short  period,  the  market  was  flooded  with 
dynamite  under  a  great  variety  of  names. 

At  present  dynamite  must  be  considered  a  generic  term 
under  which  are  included  all  mixtures  of  nitroglycerine  with 
substances  which  absorb  and  retain  it  under  ordinary  condi- 
tions of  temperature  and  pressure. 

The  material  used  as  an  absorbent  is  known  technically  as 
the  dope ;  and  according  to  the  nature  of  the  dope,  dynamites 
may  be  classified  as  follows: 

A.  DYNAMITE  WITH  AN  INERT   BASE,  e.g.,  Kieselguhr 

Dynamite. 

B.  DYNAMITE  WITH  AN  ACTIVE  BASE. 

I.   Combustible  Base,  e.g.,  Carbodynamite. 
II.  Explosive  Base. 

a.   Explosive  Mixture. 

1.  Mixture  of  the  nitrate  class,  e.g.,  Jud- 

son  Powder. 

2.  Mixture   of  the   chlorate  class,    e.g., 

Vigorite  Powder. 


GUNCOTTON  BLASTING-POWDERS  AND   DYNAMITES.    299 

b.   Explosive  Compound: 

1.  Nitro  -  substitution    compound,    e.g., 

Castellanos  Powder. 

2.  Nitric-derivative  compound,  e.g.,  Ex- 

plosive Gelatine. 

Manufacture  of  Dynamite  No.  I. — The  process  of  manu- 
facture is  similar  in  all  dynamites,  irrespective  of  the  particular 
class  to  which  they  may  belong,  and  consists  essentially  of 
preparing  the  dope,  mixing  the  purified  nitroglycerine  with 
the  dope,  and  making  and  packing  the  cartridges,  or,  when 
not  required  in  the  form  of  cartridges,  storing  the  explosive 
in  bulk. 

Ordinary  Kieselguhr  dynamite,  or  dynamite  No.  i,  con- 
sists of  a  mixture  of 

Kieselguhr 2$  parts, 

Nitroglycerine 75      ll 

Kieselguhr  is  a  substance  which  is  familiar  to  alt  under 
the  names  of  "  tripoli  "  or  "  rottenstone,"  and  possesses  in 
a  marked  degree  high  absorptive  power.  This  property, 
together  with  the  tenacity  with  which  it  retained  the  liquid 
explosive  under  considerable  changes  of  temperature;  its 
great  chemical  stability,  and  entire  inability  to  react  with 
nitroglycerine;  its  abundance  and  consequent  cheapness,  all 
combined  to  recommend  it  to  the  inventor. 

Kieselguhr  is  now  known  to  consist  of  the  inorganic 
remains  of  countless  millions  of  extremely  minute  inorganic 
beings  called  infusoria  or  diatoms. 

Enormous  deposits  of  this  infusorial  or  diatomaceous 
silica  are  to  be  found  near  Oberlohe  in  Hanover,  and  in  this 
country  a  large  deposit  has  been  traced  from  Herring's  Bay 
in  Maryland,  to  a  point  beyond  Petersburg,  Virginia;  Rich- 
mond resting  upon  a  deposit  which  is  20  feet  deep. 

When  found  it  is  more  or  less  contaminated  with  impuri- 
ties, and  it  has  to  be  calcined  to  get  rid  of  the  organic  matter. 


300  LECTURES   ON  EXPLOSIVES. 

The  reddish  tinge  often  observed  in  dynamite  is  due  to  a  little 
iron  contained  in  the  kieselguhr. 

In  a  pure  and  dry  condition,  kieselguhr  will  absorb  three 
times  its  weight  of  nitroglycerine,  and  will  retain  it  even  at 
the  highest  ordinary  temperature. 

Before  the  guhr  can  be  used  for  making  dynamite,  it  must 
be  calcined  in  order  to  eliminate  the  moisture  and  free  it  from 
the  organic  matter  it  contains. 

The  calcination  is  conducted  in  a  reverberatory  furnace, 
the  guhr  being  spread  over  the  bottom  of  the  furnace  to  a 
depth  of  four  or  five  inches,  and  heated  to  dull  redness.  The 
time  of  calcination  depends  upon  the  quality  of  the  guhr, 
which  from  time  to  time  is  turned  over  to  insure  uniformity. 
Calcined  guhr  should  not  contain  more  than  0.5  per  cent  of 
moisture  and  organic  matter.  After  being  calcined,  the  guhr 
is  crushed  between  rollers,  passed  through  fine  sieves,  dried, 
and  packed  away  in  bags,  care  being  taken  to  prevent  it  from 
absorbing  moisture. 

Before  being  mixed  with  the  dope,  the  nitroglycerine 
should  stand  for  a  day  or  two  to  "  clear,"  and  should  be 
entirely  free  from  water,  since  dynamite  containing  over  0.5 
per  cent  of  moisture  will  leak,  i.e.,  the  nitroglycerine  will 
exude  from  the  dope. 

The  nitroglycerine  is  brought  to  the  mixing-house  in 
buckets  made  of  gutta-percha  or  lacquered  compressed  wood- 
pulp  either  by  hand,  train,  or  trolley  line.  The  mixing  is 
done  by  hand,  the  guhr  being  weighed  and  placed  in  lead-lined 
tanks  and  the  nitroglycerine  poured  over  it.  As  soon  as  the 
ingredients  have  been  thoroughly  mixed,  the  dynamite  is 
rubbed  through  wire  sieves  placed  over  lead-lined  troughs, 
the  first  sieve  being  rather  coarse  (about  three  meshes  per 
linear  inch),  and  the  second  finer  (about  seven  meshes  per 
linear  inch).  In  passing  through  the  first  sieve  the  dynamite 
is  more  intimately  incorporated  than  where  merely  kneaded 
by  hand,  while  the  second  sieve  serves  to  distribute  the  nitro- 
glycerine more  uniformly  throughout  the  dope.  As  it  comes 
from  the  second  sieve,  dynamite  should  b<?  neither  too  wet 


GUNCOTTON  BLASTING-POWDERS  AND    DYNAMITES.    3OI 

nor  too  dry;  in  the  first  case  it  will  leak,  and  if  too  dry  it 
will  crumble  up  and  can  be  worked  into  cartridges  only  with 
great  difficulty. 

From  the  mixing-house  the  dynamite  is  carried  to  the 
cartridge-huts  in  small  charges  contained  in  wooden  boxes  or 
rubber  bags. 

By  far  the  greater  bulk  of  dynamite  made  is  used  for 
blasting,  and  for  this  purpose  it  is  made  into  the  shape  of 
cylinders  for  charging  bore-holes.  The  usual  sizes  of  dyna- 
mite cartridges  (as  these  cylinders  are  called),  vary  from  one 
inch  to  three  fourths  of  an  inch  in  diameter,  and  from  two  to 
eight  inches  in  length.  The  cartridges  are  formed  by  press- 
ing, the  presses  being  made  of  gun-metal,  and  only  one  press 
being  located  in  a  hut. 

Three  workmen  are  assigned  to  each  press,  one  to  work 
the  press,  while  the  other  two  receive  and  wrap  the  cartridges. 
The  press  consists  essentially  of  a  short  cylinder  of  the 
diameter  of  the  cartridge  to  be  pressed.  Into  the  cylinder 
works  up  and  down  a  piston,  the  lower  end  of  which  is  made 
of  lignum-vitae  or  ivory,  and  which  is  actuated  by  a  press- 
bar.  Attached  to  the  upper  edge  of  the  cylinder  is  a  canvas 
bag  into  which  the  powdered  dynamite  is  placed  by  means  of 
wooden  scoops,  and  as  the  piston  descends,  the  dynamite  is 
forced  into  and  through  the  cylinder,  emerging  from  the 
lower  end  in  a  compact  form,  where  it  is  broken  off  in  the 
length  of  the  required  cartridge.  Immediately  upon  leaving 
the  press  the  cartridges  are  wrapped  carefully  to  protect  them 
from  moisture.  Formerly  dynamite  was  wrapped  almost 
exclusively  in  parchment-paper,  and  this  custom  still  prevails 
in  Great  Britain.  On  the  Continent,  however,  and  in  the 
United  States  paraffined  paper  is  used. 

From  the  cartridge-huts  the  cartridges  are  taken  to  the 
packing-houses,  where  they  are  packed  either  for  storage  or 
shipment.  In  Great  Britain  and  on  the  Continent  every  five 
pounds  of  cartridges  are  first  packed  in  cardboard  boxes 
which  are  wrapped  generally  in  water-proof  paper.  Ten  such 
boxes  are  packed  in  a  light  pine  box,  the  top  of  which  is 


302  LECTURES   ON  EXPLOSIVES. 

secured  with  screws,  or  brass  or  zinc  nails.  Cardboard  boxes 
are  but  little  used  in  this  country,  the  cartridges  being  placed 
directly  in  the  wooden  boxes,  which  are  shellacked  on  the 
inside  to  render  them  water-proof.  In  every  box  of  dynamite 
is  placed  a  printed  card  of  instructions  as  to  the  danger  of  the 
explosive,  together  with  the  precautions  to  be  observed  in 
handling  and  using  it.  .  > 

With  some  dynamites  sawdust  is  used  to  fill  the  inter- 
stices between  the  cartridges  as  they  are  packed  in  boxes,  so 
that  in  case  of  "  leakage  "  during  long  storage  or  transporta- 
tion the  nitroglycerine  is  absorbed.  For  military  purposes 
dynamite  is  generally  packed  in  bulk  in  water-proof  metallic 
cases  or  bags  made  of  India-rubber. 

Properties  of  Dynamite. — Dynamite  No.  i  is  a  granular 
substance  varying  in  color  from  a  delicate  pink  to  a  dirty  gray 
or  brown,  according  to  the  kind  of  kieselguhr  used  as  an 
absorbent.  Good  dynamite  is  of  the  plastic  consistency  of 
fresh  mould.  It  should  not  feel  greasy  to  the  touch,  nor 
should  there  be  any  trace  of  free  nitroglycerine  on  the  inside 
of  the  wrapper  of  a  cartridge.  The  density  of  dynamite 
depends  upon  the  dope,  that  of  dynamite  No.  I  being  about 
1.5.  Dynamite  possesses  the  physical  properties  of  nitro- 
glycerine, which  is  its  prime  explosive  principle,  and  is  equally 
poisonous.  Its  firing-point  is  180°  C.,  and  at  this  temperature 
it  either  burns  or  explodes;  if  free  from  all  pressure,  jar,  vibra- 
tion, or  force  of  any  kind,  it  burns;  otherwise  it  explodes. 
The  sensitiveness  of  dynamite  to  blows  or  shocks  increases 
rapidly  with  the  temperature,  so  that,  according  to  Eissler, 
"  at  350°  F.  the  fall  upon  it  of  a  dime  will  explode  it." 
High  temperatures  below  its  firing-point  cause  dynamite  "  to 
leak"  ;  hence  it  should  always  be  carefully  tested,  and  made  to 
resist  exudation  at  the  highest  temperature  to  which  it  may 
be  subjected.  When  ignited  in  small  quantities  in  the  open 
air  it  simply  burns  fiercely,  but  when  larger  amounts  are 
ignited  explosion  almost  invariably  results,  the  explanation 
being  obvious. 

Dynamite  freezes  at  about  4°  C.,  and  when  once  frozen  it 


GUNCOTTON  BLASTING-POWDERS  AND    DYNAMITES     303 

remains  in  this  condition  at  temperatures  considerably  exceed- 
ing this.  Solidly  frozen,  it  cannot  be  detonated  except  with 
great  difficulty,  and  then  at  a  very  great  loss  of  its  explosive 
force.  Although  nitroglycerine  is  rendered  practically  safe 
by  freezing  it  is  nevertheless  dangerous  to  cut  a  frozen  dyna- 
mite cartridge  with  a  knife,  or  to  ram  frozen  cartridges  in 
bore-holes.  It  is  therefore  customary  to  thaw  the  frozen 
explosive  before  using  it.  This  operation  requires  great  care, 
and  it  is  very  easily  performed,  yet  the  great  number  of  fatal 
accidents  which  have  resulted  either  through  ignorance  or 
criminal  neglect  or  total  disregard  of  the  instructions  issued 
with  each  package  of  the  explosive  as  to  how  to  perform  the 
operation,  has  served  in  a  great  measure  to  prejudice  the 
popular  mind  against  dynamite.  In  each  and  every  case  the 
accident  can  be  traced  to  the  responsible  person  or  persons, 
and  a  few  criminal  proceedings  in  this  country  such  as  invari- 
ably follow  such  "  murders  "  or  suicides  "  in  England  would 
have  a  very  wholesome  effect. 

These  accidents  are  generally  due  to  the  erroneous  sup- 
position that  because  it  is  reasonably  safe  to  ignite  a  cartridge 
of  unfrozen  dynamite,  it  is  equally  safe  to  warm  it  upon  a 
shovel,  or  in  a  tin  can,  or  in  an  oven;  whereas  when  heated 
in  this  manner  the  danger  limit  is  approached  with  each  suc- 
ceeding degree  of  temperature.  All  nitroglycerine  prepara- 
tions, when  gradually  heated  up  to  their  exploding  points, 
become  extremely  sensitive  to  the  least  shock  or  blow,  and  once 
that  point  is  reached,  they  no  longer  simply  ignite,  but 
explode  with  great  violence;  and  further,  owing  to  the  poor 
conductivity  of  the  material,  a  small  portion  of  dynamite  in 
contact  with  the  source  of  heat  may  reach  this  point  and  cause 
the  explosion  of  the  rest  of  the  mass,  which  may  be  consider- 
ably below  the  danger  point. 

The  necessary  precautions  to  be  observed  in  thawing  nitro- 
glycerine and  its  compounds,  and  the  safest  manner  in  which 
this  operation  may  be  conducted,  have  already  been  enumer- 
ated and  described  in  a  previous  lecture.  That  dynamite  is 
liable  to  spontaneous  decomposition  is  a  very  common  but 


3°4  LECTURES   ON  EXPLOSIVES. 

erroneous  idea.  Equally  untrue  are  the  statements  that 
dynamite  may  be  exploded  by  dropping  a  cartridge  upon  the 
ground,  or  by  the  shock  caused  by  slamming  a  door  or  win- 
dow. It  is,  however,  true  that  dynamite  made  from  impure 
nitroglycerine  decomposes  under  climatic  variations,  and 
especially  when  subjected  to  extremely  high  temperatures, 
and  while  in  the  state  of  decomposition  it  is  more  sensitive 
to  shock  than  when  perfectly  stable.  For  this  reason  it  is 
often  desirable  to  destroy  dynamite  which  has  developed 
signs  of  decomposition.  The  simplest  and  most  effective 
way  to  accomplish  this  object,  according  to  Dr.  Dupre,  is  to 
place  the  cartridges  or  loose  dynamite  upon  the  ground  in  long 
trains,  pour  paraffin  oil  over  the  mass,  and  set  fire  to  one  end. 
The  combustion  will  proceed  quietly  and  without  danger. 

The  sensitiveness  of  dynamite  to  shock  depends  largely 
upon  the  dope.  Generally  speaking,  dynamite  does  not 
explode  by  blows  of  wood  upon  wood,  but  is  liable  to  do  so 
when  struck  between  stones,  and  always  explodes  when  the 
blow  is  of  metal  upon  metal,  except  copper  and  lead. 

Dynamite  when  packed  in  the  form  of  cartridges  or  as 
loose  powder  will  stand  very  rough  handling  under  ordinary 
circumstances,  since  on  account  of  its  plastic  nature  it  requires 
a  severe  blow  to  develop  sufficient  heat  to  raise  the  particles 
struck  to  the  exploding-point.  Boxes  of  dynamite  have  been 
dropped  in  quarries  from  heights  of  150  feet  without  explod- 
ing; and  bullets  fired  from  the  service  rifle  will  cause  explosion 
upon  impact  only  at  distances  less  than  60  paces.  The  sub- 
ject of  sympathetic  explosion,  or  the  explosion  of  one  mass 
of  dynamite  by  a  second  mass  fired  in  the  vicinity  of,  but  not 
in  contact  with,  the  first  mass,  will  be  considered  later. 

Dynamite  with  an  Active  Base. — Very  soon  after  the 
introduction  of  dynamite  it  was  discovered  that  one  of  the 
very  properties  of  the  new  explosive  by  virtue  of  which  its 
inventor  claimed  for  it  superiority  over  all  other  blasting 
agents,  namely,  its  tremendous  power,  rendered  it  wholly 
unfit  for  certain  kinds  of  work,  such  as  mining  coal,  quarrying 
rock  for  building  purposes,  etc.  In  all  such  work,  as  also  in 


GUNCOTTON  BLASTING-POWDERS  AND   DYNAMITES.    305 

working  in  soft  coal  and  earth,  Dynamite  No.  I  was  found  to 
be  less  efficient  than  black  powder.  As  the  energy  of  the 
explosive  was  entirely  dependent  upon  the  nitroglycerine 
contained  in  it,  it  was  a  very  simple  problem  to  regulate  its 
force.  To  reduce  this  energy  and  moderate  the  violence  of 
the  explosion  it  was  only  necessary  to  reduce  the  percentage 
of  nitroglycerine  in  the  dynamite.  Experience  has  proven 
this  to  be  true,  but  only  up  to  a  certain  point,  so  far  as  it 
concerns  Dynamite  No.  i,  since  it  is  claimed  that  a  kieselguhr 
dynamite  containing  less  than  30  per  cent  of  nitroglycerine 
cannot  be  exploded. 

In  the  case  of  dynamites  having  active  bases,  however,  the 
proportion  of  nitroglycerine  may  be  reduced  to  less  than  5  per 
cent,  and  the  resulting  explosive  still  be  susceptible  of  explo- 
sion. As  before  stated,  dynamites  with  active  bases  may  be 
subdivided  into  two  classes,  according  as  the  base  is  a  com- 
bustible or  an  explosive.  The  principle  involved  in  these 
powders  is  to  substitute  for  a  perfectly  inert  base  an  absorbent 
which  will  not  only  retain  the  nitroglycerine,  but,  by  its  own 
combustion  or  explosion,  either  admit  of  the  percentage  of 
nitroglycerine  being  reduced  below  the  limit  possible  with 
ordinary  dynamite,  thus  diminishing  the  force  of  the  explo- 
sive; or,  on  the  other  hand,  retaining  the  same  amount  of 
nitroglycerine,  by  the  addition  of  its  own  force,  producing  a 
still  more  powerful  explosive. 

Dynamite  with  a  Combustible  Base — Carbodynamite. 
— As  an  example  of  this  class,  carbodynamite  may  be  men- 
tioned as  one  of  the  most  recently  patented  and  most  favor- 
ably received.  It  consists  of  90  parts  or  less  of  nitroglycerine 
and  10  parts  of  very  absorbent  charcoal,  obtained  by  carboniz- 
ing cork.  To  every  100  parts  of  the  explosive  is  added  1.5 
parts  of  sodium  or  ammonium  carbonate.  In  one  variety 
water  is  added  with  the  view  of  rendering  the  dynamite 
uninflammable.  This  explosive  does  not  disintegrate  or 
"  leak  "  when  exposed  to  the  action  of  water.  It  is  a  black, 
somewhat  friable  substance,  and  compares  very  well  with 
other  dynamites  of  the  same  grade. 


306  LECTURES   ON  EXPLOSIVES. 

Another  explosive  of  this  class  very  similar  to  carbo- 
dynamite  is  Punshori s  Explosive,  in  which  30  parts  of 
carbonized  or  charred  peat  are  used  to  absorb  70  parts  of 
nitroglycerine.  In  the  preparation  of  the  explosive  the 
nitroglycerine  *'  is  cleaned  by  means  of  chalk  mixed  with 
water  instead  of  by  the  use  of  alkalies." 

Dynamite  with  an  Explosive  Base. — Dynamites  with 
explosive  bases  may  be  classified  according  as  the  base  is  an 
explosive  mixture  or  an  explosive  compound,  and  again, 
further  subdivided  according  as  the  base  belongs  (i)  to  mix- 
tures of  the  nitrate  or  of  the  chlorate  class,  or  (2)  to  compounds 
of  the  nitro-substitution  or  nitric  derivatives. 

Dynamite  with  a  Nitrate  Mixture  Base. — One  of  the 
simplest  and  earliest  powders  of  this  class  consisted  of  a 
mixture  of  nitroglycerine  and  mealed  gunpowder.  In  addi- 
tion to  the  increased  safety  of  the  powder  over  that  of  nitro- 
glycerine in  a  liquid  state,  it  was  claimed  that  the  new  powder 
was  much  more  powerful  than  ordinary  dynamite,  and  that 
the  power  actually  developed  was  considerably  greater  than 
the  sum  of  the  forces  of  the  two  ingredients  fired  separately. 
In  explanation  and  support  of  this  claim  the  inventor  asserted 
that  when  fired  the  gunpowder  was  detonated  by  the  nitro- 
glycerine, it  being  well  known  that  the  force  developed  by 
gunpowder  when  detonated  is  something  greater  than  four 
times  that  observed  when  it  is  simply  exploded.  This  par- 
ticular powder  was  followed  by  others  too  numerous  to  be 
mentioned. 

Dynamite  No.  2. — This  explosive  was  introduced  to  com- 
pete with  powders  ordinarily  used  where  great  power  and 
local  effect  was  not  desired,  such  as  for  work  in  coal-mines, 
etc.  It  consists  of 

Nitroglycerine 1 8  parts 

Potassium  nitrate 71      " 

Charcoal IO      " 

Paraffin..  I      " 


GUNCOTTON  BLASTING-POWDERS  AND    DYNAMITES.    307 

Dynamite  with  a  Chlorate  Mixture  Base. — As  an  exam- 
ple of  dynamites  of  this  class  may  be  mentioned: 

Vigorite,  a  powder  manufactured  by  the  California 
Vigorite  Powder  Company,  one  grade  of  which  has  the  follow- 
ing composition: 

Nitroglycerine 30  parts 

Potassium  chlorate 49     *  * 

Potassium  nitrate 7     " 

Magnesium  carbonate 5      " 

Wood  pulp  (or  fibre) 9      " 

All  dynamites  of  this  class  possess  to  a  greater  or  less  degree 
the  dangers  inherent  to  all  chlorate  mixtures. 

Dynamite  with  a  Nitro-substitution  Product  Base.— 
Comparatively  few  dynamites  under  this  class  have  attained 
any  practical  value;  one  of  the  principal  ones  is  known  as 

Castellanos  Powder,  which  consists  of  a  mixture  of  nitro- 
glycerine, nitrobenzole,  fibrous  material,  and  guhr.  A  second 
variety  of  this  powder  having  the  following  composition  has 
been  suggested: 

Nitroglycerine 40  parts 

Picrate   10     ' ' 

Sodium  nitrate 25      '  * 

Carbon 10     " 

Sulphur 5      " 

Insoluble  salt. 10     " 

The  insoluble  salt  may  be  a  silicate  of  zinc,  magnesium,  or 
calcium,  oxalate  of  calcium,  carbonate  of  zinc,  etc. 

Dynamite  with  a  Nitric  Derivative  Base. — If  we  exam- 
ine the  equations  supposed  to  represent  the  reactions  which 
occur  upon  the  explosion  of  nitroglycerine  and  guncotton 
respectively,  it  will  be  seen  that  when  nitroglycerine  is 
detonated  free  oxygen  is  evolved,  while  when  guncotton  is 
detonated  we  have  a  product  of  incomplete  combustion  in  the 
form  of  carbon  monoxide.  If,  therefore,  these  two  explosives 


308  LECTURES   ON  EXPLOSIVES. 

can  be  so  combined  as  to  use  the  excess  of  oxygen  in  the  one 
to  produce  complete  combustion  in  the  other,  we  should  have 
theoretically  a  far  more  powerful  explosive  than  either  of  the 
constituents  alone. 

Explosive  Gelatine,  or  Blasting  Gelatine.  —  In  1875 
Mr.  Alfred  Nobel  patented  a  process  by  which  soluble  gun- 
cotton  was  dissolved  in  nitroglycerine  by  the  aid  of  heat,  the 
result  being  a  tough  jelly-like  mass  which  was  called  explo- 
sive or  blasting  gelatine.  The  percentage  of  nitrocotton  in 
explosive  gelatine  varies  from  4  to  8  per  cent.  The  nitro- 
cotton used  should  contain  not  more  than  1 1  per  cent  of 
nitrogen,  and  upon  ignition  should  leave  not  more  than  0.25 
per  cent  of  ash.  Before  mixing  with  nitroglycerine  it  is 
thoroughly  dried  and  very  finely  comminuted.  The  nitro- 
glycerine is  also  very  carefully  dried  beforehand,  since  the 
presence  of  traces  of  water  in  the  ingredients  almost  invariably 
causes  the  gelatine  "  to  leak."  In  smaller  factories  the 
nitroglycerine  is  poured  into  troughs  made  of  sheet  copper, 
which  are  surrounded  by  water-jackets  through  which  water 
heated  to  about  40°  C.  is  made  to  circulate.  As  soon  as  the 
nitroglycerine  is  heated,  the  time  required  varying  from  one- 
half  to  one  hour,  the  nitro-cotton  is  added  and  stirred  in  by 
means  of  wooden  spades  until  the  mass  is  thoroughly  mixed, 
and  then  allowed  to  stand  for  two  hours.  At  the  end  of  that 
time  it  is  kneaded  by  hand  until  it  has  a  jelly-like  consistency, 
the  water  is  drawn  off,  and  the  mass  allowed  to  cool. 

In  larger  factories,  special  kneading  or  mixing  machines 
are  substituted  for  the  hand  process  just  described. 

On  account  of  its  toughness,  explosive  gelatine  cannot  be 
made  into  cartridges  as  readily  as  ordinary  dynamite,  but 
requires  a  special  machine  for  that  purpose. 

A  very  satisfactory  machine  for  making  gelatine  cartridges 
is  made  upon  the  principle  of  an  ordinary  sausage-making 
machine,  and  consists  of  a  conical  case  containing  a  concentric 
shaft  and  screw  blade,  the  bearings  of  the  shaft  being  outside 
of  the  casing.  An  opening  in  the  top  of  the  case  is  fitted  with 
a  funnel  through  which  the  gelatine  is  introduced  into  the 


GUNCOTTON  BLASTING-POWDERS  AND   DYNAMITES.    309 

machine,  and  a  second  opening  at  the  apex  of  the  cone  is 
fitted  with  a  nozzle  (of  the  diameter  of  the  cartridge),  through 
which  the  gelatine  is  forced  out  in  the  form  of  a  long  cylin- 
der. All  of  the  parts  of  the  machine  are  made  of  gun-metal. 
As  the  cylinder  of  gelatine  issues  from  the  press,  it  is  cut  into 
lengths  by  means  of  a  double-bladed  knife,  the  blades  being 
separated  at  the  distance  equal  to  the  desired  length  of  the 
cartridge.  The  cartridges  are  then  wrapped  and  packed  as 
already  described  in  the  case  of  dynamite. 

Properties  of  Explosive  Gelatine. — Explosive  gelatine  is 
a  translucent  elastic  substance,  varying  in  color  from  bright 
yellow  to  yellowish  brown.  It  has  a  specific  gravity  of  1.6. 
It  does  not  absorb  water,  and  when  placed  in  it,  is  affected 
only  superficially,  a  very  small  quantity  of  nitroglycerine 
being  dissolved  from  the  surface,  which  assumes  a  whitish 
color;  but  no  further  change  occurs,  no  matter  how  long  the 
explosive  remains  immersed. 

Unconfined  it  burns,  when  ignited,  with  a  bright-yellow 
flame  and  a  hissing  sound,  but  does  not  explode.  If,  how- 
ever, it  is  confined  and  heated  to  its  ignition-point,  it  explodes 
violently.  Heated  slowly  it  explodes  at  204°  C.  (399°  F.); 
heated  rapidly  it  explodes  at  240°  C.  (464°  F.).  At  low 
temperatures  it  freezes  into  a  hard  solid  of  paler  yellow  color 
than  when  in  its  normal  state,  and  seems  to  assume  a  crystal- 
line structure. 

The  exact  temperature  at  which  it  freezes  has  not  been 
definitely  ascertained,  as  some  cartridges  have  been  found  to 
resist  freezing  when  exposed  to  a  freezing  mixture  for  twenty- 
four  hours,  while  others  have  frozen  readily  at  2°  to  4°  C. 
(35°  to  40°  F.).  Unlike  several  dynamites  previously  consid- 
ered, explosive  gelatine  is  much  more  sensitive  when  frozen 
than  when  in  the  unfrozen  state,  and  can  be  readily  detonated 
or  exploded  by  the  impact  of  bullets. 

When  well  made,  explosive  gelatine  will  not  exude  nitro- 
glycerine even  after  repeated  freezing  and  thawing,  or  when 
subjected  to  a  temperature  of  90°  F.  for  144  hours.  Ordi- 
narily gelatine  requires  very  strong  detonators  in  order  to 


310  LECTURES   ON  EXPLOSIVES. 

develop  its  full  force,  the  strength  of  the  detonator  varying, 
however,  with  the  percentage  of  nitrocotton  in  the  explosive. 
To  insure  an  explosion  of  the  first  order,  it  is  advisable  to  use 
at  least  one  gramme  of  fulminate  in  firing  explosive  gelatine. 
Blasting  gelatine  seems  to  be  gradually  supplanting  all  other 
forms  of  dynamite,  both  in  this  country  and  abroad. 

Military  Explosive  Gelatine.  —  The  investigations  of 
Siersch  and  Roth  in  connection  with  those  of  Trauzl  and 
Colonel  Hess  have  demonstrated  that  the  addition  of  a  small 
percentage  of  camphor  to  ordinary  explosive  gelatine  greatly 
diminishes  its  sensitiveness  to  shock,  and  especially  to  the 
impact  of  bullets  at  short  range.  Such  an  explosive  was 
introduced  in  Austria  under  the  name  of  military  explosive 
gelatine,  and  has  the  following  composition: 

Nitroglycerine 90  parts  ) 

_  ,   ,  ?  J  \  Explosive  gelatine —   06  parts 

Soluble  guncotton.    10  J 

Camphor  4     " 

In  Italy  these  proportions  are  slightly  varied,  the  military 
gelatine  consisting  of  92  parts  of  nitroglycerine,  8  parts  of 
nitrocotton,  and  5  parts  of  camphor. 

In  appearance  the  military  explosive  gelatine  resembles 
ordinary  explosive  gelatine,  but  it  emits  the  odor  of  camphor, 
and  with  the  exception  of  the  increased  insensitiveness,  its 
properties  are  the  same. 

Berthelot  holds  that  the  effect  of  the  camphor,  in  increas- 
ing the  insensitiveness  of  the  explosive,  results  from  the 
increased  elasticity  and  solidity  which  the  explosive  thus 
acquires,  in  consequence  of  which  the  initial  shock  of  the 
detonator  is  propagated  through  a  much  greater  mass  of  the 
substance  than  it  would  be  if  the  camphor  were  not  present, 
so  that  the  sudden  and  local  elevation  of  the  temperature, 
which  is  necessary  for  the  chemical  and  mechanical  action 
which  results  in  detonation,  is  not  realized  except  by  the  use 
of  a  very  powerful  detonator.  Camphor,  according  to  this 
theory,  does  not  exert  any  action  on  discontinuous  powders, 
and  this  is  shown  in  practice  with  potassium  chlorate  powders. 


G  UNCO TTON  BLA S  TING-PO  WDERS  AND    D  YNA MITES.    3 1 1 

On  account  of  its  solid  form  and  plastic  nature,  its  great 
power  and  insensitiveness,  explosive  gelatine  has  been 
regarded  as  the  ideal  military  explosive,  but  unfortunately  it 
has  in  several  instances  decomposed  during  storage,  and 
without  any  apparent  cause.  One  such  case  of  decomposition 
is  recorded  by  Professor  Munroe,  of  the  U.  S.  Naval  Torpedo 
Station,  and  others  have  been  noted,  although  no  explosions 
resulted.  At  the  Artillery  School  a  package  containing  fifty 
pounds  was  subjected  to  considerable  variations  of  tempera- 
ture for  six  years,  and  on  one  occasion  was  immersed  in  sea- 
water  for  four  days,  and  when  samples  were  subjected  to 
service  tests  no  signs  of  decomposition  were  discovered, 
while,  tested  in  the  pressure-gauge,  it  showed  most  conclu- 
sively that  it  had  lost  none  of  its  explosive  force. 

Berthelot  finds  the  theoretical  pressure  of  this  explosive 
to  be  nearly  identical  with  that  of  nitroglycerine.  F.  von 
Rzilia  finds  its  theoretical  efficiency  to  be  less  than  that  of 
nitroglycerine  in  the  ratio  of  1.40  to  1.45,  and,  from  the  dis- 
cussion of  extensive  data  practically  obtained,  he  supports  his 
conclusion. 

General  Abbot,  however,  finds  the  relative  intensity  of 
Dynamite  No.  I,  nitroglycerine  and  explosive  gelatine,  when 
fired  under  water  to  be  as  100  :  81  :  117;  and  with  a  sample 
of  explosive  gelatine  furnished  by  Nobel's  Explosive  Com- 
pany of  Glasgow  he  obtained  a  relative  intensity  of  142. 

In  the  experiments  with  the  Quinan  Pressure-gauge,  con- 
ducted at  the  Artillery  School,  these  intensities  were  as  8 1 . 3 1  : 
81.85  :  106.17. 

Gelatine  Dynamite. — Under  this  name  are  classed  explo- 
sives of  the  explosive  gelatine  type,  whose  explosive  force  has 
been  modified  by  the  admixture  of  various  substances.  For 
general  purposes  explosive  gelatine  is  too  powerful,  its  use 
being  limited  to  blasting  very  tough  rock  and  to  military  pur- 
poses. 

As  in  the  case  of  ordinary  dynamite,  by  making  a  thinner 
gelatine  and  incorporating  it  with  a  suitable  dope,  it  is  possi- 
ble to  make  an  explosive  which  possesses  all  of  the  physical 


312  LECTURES   ON  EXPLOSIVES. 

characteristics  of  explosive  gelatine,  and  the  force  of  which 
may  be  regulated  according  to  the  nature  of  the  dope.  This 
subclass  of  explosives  is  midway  between  ordinary  dynamite 
and  explosive  gelatine,  and  is  known  as  gelatine  dynamite. 

Forcite  is  a  gelatine  dynamite  largely  used  in  the  United 
States,  and,  on  account  of  its  great  strength,  stability,  and 
cheapness  as  compared  with  the  cost  of  explosive  gelatine,  it 
has  been  proposed  as  a  service  explosive  for  charging  military 
submarine  mines.  The  American  letters-patent  for  this 
explosive  describe  it  as  a  combination  of  nitroglycerine  with 
u  an  inexplosive  gelatinizing  material  and  an  oxidizing  salt." 
The  analysis  of  one  sample  of  forcite  showed  its  composition 
to  be  as  follows: 

Nitroglycerine 98  parts  )   _  .     . 

,T.      &*  \  Gelatine 50  parts 

Nitrocotton 2  ) 

Sodium  nitrate 76  parts 

Sulphur..  3      " 

Wood-tar 20     « 

Wood-pulp I      " 

Tests  for  Dynamite. — Generally  speaking,  the  tests  for 
various  dynamites,  except  in  the  case  of  actual  analysis, 
consist  in  the  determination  of  the  quality  of  the  nitro- 
glycerine which  forms  the  active  principle  of  the  explosive. 

Separation  of  the  Nitroglycerine  from  the  Base. — In 
order  to  test  the  nitroglycerine,  it  is  first  necessary  to  separate 
it  from  the  base,  and  this  is  done  as  follows: 

About  25  grammes  of  the  dynamite  are  placed  in  a  glass 
funnel  which  has  previously  been  thoroughly  cleaned  and 
plugged  with  asbestos.  The  surface  is  smoothed  with  a  flat- 
headed  glass  rod,  and  kieselguhr,  clean  and  dried,  spread  over 
it  to  the  depth  of  about  one  eighth  of  an  inch.  Water  is  next 
added  until  the  layer  of  kieselguhr  is  thoroughly  moistened, 
and  a  clean,  dry  test-tube  is  placed  under  the  funnel  to  catch 
the  nitroglycerine.  Water  is  added  from  time  to  time  until 
sufficient  nitroglycerine  is  collected  for  the  several  tests.  If 
any  water  passes  through  with  the  nitroglycerine,  it  is  removed 


G  UNCO  TTON  BLA  S TING-PO  WDERS  A ND   D  YNA  MITES.    3 1 3 

•with  a  piece  of  blotting-paper,  or,  if  necessary,  the  nitro- 
glycerine is  filtered  through  a  dry  filter. 

Test  for  Free  Acid  in  Dynamite. — For  this  test  it  is  not 
absolutely  necessary  that  the  nitroglycerine  be  separated,  but 
if  that  has  been  done,  proceed  exactly  as  in  the  test  for  ordi- 
nary nitroglycerine.  Generally  it  is  only  necessary  to  put 
about  one  gramme  of  the  explosive  in  a  perfectly  clean  test- 
tube,  and  half  fill  the  tube  with  distilled  water.  The  tube  is 
then  closed  with  the  thumb  and  shaken  vigorously  for  two  or 
three  minutes.  As  soon  as  the  dynamite  settles  to  the  bottom 
of  the  tube  the  water  is  tested  for  acidity  in  the  usual  way. 

Stability  and  Nitrogen  Tests  for  Dynamite. — These 
tests  are  conducted  in  precisely  the  same  manner  as  has 
already  been  described  for  nitroglycerine,  the  sample  to  be 
tested  being  taken  from  the  nitroglycerine  which  has  been 
separated  from  the  base  as  above  indicated. 

Stability  Tests  for  Explosive  Gelatine  and  Gelatine 
Dynamite. — In  the  case  of  explosive  gelatine  it  is  necessary 
to  especially  prepare  the  explosive  before  subjecting  it  to  the 
Heat  or  Stability  Test. 

About  one  and  one-half  grammes  of  the  gelatine  are  incor- 
porated with  twice  the  quantity  of  French  chalk  by  working 
them  together  gently  in  a  porcelain  dish  with  a  wooden 
spatula. 

When  intimately  mixed,  enough  of  the  mixture  is  intro- 
duced carefully  into  the  test-tube,  so  that  when  it  is  gently 
compressed  it  will  fill  the  tube  to  the  depth  of  about  if 
inches. 

The  rest  of  the  test  is  conducted  as  already  described, 
except  that  the  temperature  of  the  bath  is  kept  at  160°  F., 
and  the  time  allowed  before  discoloration  of  the  fest-paper 
appears  is  10  minutes. 

Liquefaction  Tests  for  Explosive  Gelatine  and  Gelatine 
Dynamite — In  addition  to  the  usual  tests  to  which  all  nitro- 
glycerine preparations  are  subjected,  there  is  an  additional 
test  which  is  applied  to  explosive  gelatine,  known  as  the 
liquefaction  test.  To  make  this  test,  a  cylinder  is  cut  from  a 


3J4  LECTURES   ON  EXPLOSIVES. 

gelatine  cartridge  or  stick,  the  length  of  which  is  equal  to  its 
diameter,  the  ends  being  perfectly  flat.  The  cylinder  is  then 
secured  to  a  perfectly  flat  surface  by  means  of  a  pin  passing 
vertically  through  its  centre,  and  exposed  to  a  temperature 
from  85°  to  90°  F.  for  six  days  and  nights  (144  hours). 
During  such  exposure  the  cylinder  should  not  diminish  more 
than  one  fourth  of  its  original  length,  and  the  upper  cut  sur- 
face should  retain  its  flatness  and  the  sharpness  of  its  edge. 

The  test  of  liability  to  exudation  of  gelatine  requires  that 
there  shall  be  no  separation  of  the  general  mass  of  the  sample 
to  be  tested  of  a  substance  of  less  consistency  than  the  bulk 
of  the  remaining  portion  of  the  material  under  any  condition 
of  storage,  transport,  or  use,  or  when  the  material  is  subjected 
three  times  in  succession  to  alternate  freezing  and  thawing, 
or  when  subjected  to  the  liquefaction  test  hereinbefore 
described. 

In  addition  to  these  tests  for  dynamite,  which  are  readily 
made  and  require  no  particular  knowledge  of  the  chemical 
principles  involved,  it  is  sometimes  necessary  to  determine 
more  fully,  not  only  qualitatively,  but  quantitatively,  the 
character  of  nitroglycerine  preparations. 

It  is  impossible  to  explain  in  detail  the  exact  method  of 
procedure  in  the  case  of  every  dynamite.  The  following 
outline  scheme,  however,  indicates  the  general  method  to  be 
pursued  in  the  analysis  of  nitroglycerine  and  nitrocotton  pow- 
ders, and  the  operator  will  have  little  difficulty  in  applying  it 
to  particular  cases. 


GUN  COT  TON  BLASTING-POWDERS  AND   DYNAMITES.    31$ 


Outline    Scheme   for    the  Analysis   of  Nitroglycerine 
Preparations, 


I.    Exhaust  the  previously  dried  substance  with  anhydrous 
ether,  preferably  in  a  fat-extraction  apparatus,      (i  and  2.) 

i.     Solution:  Divide  into  two  equal  parts.      (A  and  B.) 


A.  Allow  the  ether  to  evap- 
orate spontaneously,  dVy 
the  residue  in  a  vacuum  of 
H3SO4 ,  and  weigh. 
Weight  represents  nitro- 
glycerine, resin,  camphor,1 
(sulphur2)  and  paraffin. 

1.  Determine  the  camphor  by 
difference. 

2.  As  sulphur  is  very  sparingly 
soluble  in  ether,  it  is  pref- 
erable to   extract   some   of 
the  original  substance  with 
water,  and  treat  the  residue 
with  alcoholic  potash,  add 
bromine,  acidify,  and  pre- 
cipitate as  BaSO4. 


B.  Add  phenolphthalein  and 
titrate  with  alcoholic  potash 
(i  c.c.  NKHO  =  0.330 
resin).  Add  considerably 
more  KHO; 
dissolve  the 
water,  shake 
and  separate. 


evaporate, 

residue     in 

with    ether, 


Ethereal 
Solution. 


Evaporated, 

leaves  the 

paraffin. 


Aqueous 
Liquid. 


Add  bromine, 
and  acidify 
with  HC1.  Sep- 
arate1 the  resin, 
and  precipitate 
with  BaCl2.3 

1.  By     filtra- 
tion. 

2.  BaSO4    X 
0.1374  =  Sul- 
phur. 


LECTURES   ON  EXPLOSIVES. 


2.      Residue :   Dry,  weigh,  and   exhaust  with  water  in  an 
extraction-apparatus.     (C  and  D.) 


C.   Solution  : 

D.   Residue  : 

Contains  metals,  nitrates, 
chlorates,  soluble  carbonates, 
etc.,  the  sum  of  which  (except 
(NH4)3CO3)  can  be  deter- 
mined by  evaporating  the  so- 
lution to  dryness  at  100°  C., 
and  weighing  the  residue.  The 
nitrates  can  be  conveniently 
determined  by  a  nitrometer. 

Dry,  weigh,  and  agitate  ali- 
quot part  with  H2SO4  and  Hg 
in  a  nitrometer.  Evolved  gas 
=•  NaO2  for  cellulose  nitrates. 
If  any  N2O4  is  evolved,  treat 
the  remaining  part  of  residue 
with  a  mixture  of  2  parts  of 
ether  and  I  part  of  absolute 
alcohol.  (E  and  F.) 

E.   Solution  : 

F.   Residue: 

Evaporate  and  weigh  the  res- 
idue, which  consists  of  mono- 
and  di-nitrocellulose,  and  col- 
lodion guncotton.  This  may 
be  further  examined  by  the 
nitrometer. 

Dry,  weigh,  and  treat  a 
weighed  portion  in  nitrome- 
ter, calculating  evolved  gas  to 
tri-nitrocellulose.  If  present, 
exhaust  the  remaining  part  of 
residue  with  acetic  ether.  (G 
and  H.) 

G.    Solution  : 

H.   Residue: 

Contains  tri-nitrocellulose. 

Weigh,  ignite,  and  weigh 
again.  Loss  of  weight  re- 
presents sawdust,  cellulose  of 
kieselguhr,  charcoal,  chalk, 
and  other  mineral  matter. 

GUNCOTTON  BLASTING-POWDERS  AND    DYNAMITES.    3 1/ 

Suggestions  on  the  Analysis  of  Nitroglycerine  Pow- 
ders.— The  following  suggestions  will  be  of  value  to  the 
beginner  in  following  the  outline  scheme  given  above.  In 
order  to  thoroughly  dry  the  substance  so  as  to  determine  the 
percentage  of  moisture  and  also  prepare  it  for  further  manipu- 
lation, finely  divide  and  weigh  out  10  or  15  grammes  and  place 
in  a  desiccator  for  6  or  8  days,  and  then  reweigh.  Note  loss 
of  weight,  replace  in  desiccator,  and  reweigh  after  4  hours. 
Repeat  this  operation  until  constant  weight  obtains,  and  total 
loss  of  weight  gives  the  moisture.  In  the  case  of  ordinary 
dynamites,  it  is  only  necessary  to  crumble  it  in  the  hands,  or 
force  it  through  a  sieve  before  placing  it  in  the  desiccator;  but 
gelatine  powders  must  be  carefully  divided  into  small  pieces 
by  means  of  a  clean  platinum  or  steel  spatula. 

The  dried  sample  or  a  portion  of  it  is  next  transferred  to 
the  extractor  funnel,  the  stem  of  which  has  been  previously 
plugged  with  glass,  wool,  or  asbestos  fibre,  and  the  funnel 
and  explosive  are  weighed,  and  transferred  to  the  extraction 
apparatus.* 

The  selection  of  a  solvent  requires  careful  attention, 
depending  upon  the  nature  of  the  explosive  under  examina- 
tion. Anhydrous  ether  alone  dissolves  out  the  nitroglycerine, 
leaving  the  nitrocotton,  if  present,  in  the  solid  residue,  whence 
it  is  subsequently  removed  by  means  of  an  ether-alcohol  solu- 
tion, A  more  expeditious  method  of  determining  the  nitro- 
cotton is  to  treat  the  dried  weighed  sample  in  a  flask  with 
250  c.c.  of  ether-alcohol  (2  parts  of  ether  to  I  part  of  alcohol) 
and  allow  it  to  stand  for  12  hours.  The  solution  is  then 
filtered,  the  residue  treated  with  an  additional  100  c.c.  of 
ether-alcohol,  which  at  the  end  of  20  minutes  is  poured  on 
the  filter,  and  the  filtrate  added  to  that  obtained  from  the  first 
treatment.  The  nitrocotton  is  next  precipitated  from  the 
solution  by  means  of  chloroform  (about  100  c.c.  are  necessary) 
and  the  solution  filtered  through  a  linen  filter.  The  precipi- 

*  Any  extraction  apparatus  may  be  used,  but  on  account  of  its  simplic- 
ity and  the  excellent  results  obtained  with  it  the  Soxhlet  apparatus  is 
recommended. 


LECTURES   ON  EXPLOSIVES. 

tated  nitrocotton  is  dried  on  the  filter,  then  detached  from  it, 
redissolved  in  ether-alcohol,  again  precipitated  with  chloro- 
form, filtered,  dried,  detached,  dried  again  to  constant 
weight,  and  weighed  for  the  percentage  of  nitrocotton. 

When  ether  alone  is  used  in  the  extraction  apparatus,  the 
solution  contains  the  nitroglycerine,  resin,  camphor,  and 
paraffin,  while  the  nitrocotton,  metallic  salts,  wood-pulp,  etc., 
remain  undissolved. 

The  manipulation  of  solution  (A)  in  the  scheme  may  be 
explained  as  follows:  The  dried,  weighed  residue  is  treated 
with  solution  of  sodium  hydrate  on  a  water-bath,  which  dis- 
solves out  the  resin.  From  this  solution  the  resin  may  be 
precipitated  by  HC1,  collected  on  a  weighed  filter,  dried,  and 
its  weight  determined.  The  paraffin  may  be  separated  from 
the  sulphur  (after  the  resin  has  been  removed)  by  heating  the 
residue  with  a  solution  of  ammonium  sulphide.  Upon  cool- 
ing the  paraffin  forms  upon  the  surface  of  the  solution  as  a 
solid  crust,  and  by  puncturing  the  crust  with  a  glass  rod  the 
liquid  may  be  poured  off,  the  paraffin  washed  with  distilled 
water,  dried,  and  weighed. 

The  camphor,  being  readily  volatile,  may  be  separated 
from  the  sulphur  (after  the  resin  and  paraffin  have  been 
eliminated)  by  treating  the  residue  with  CS3  and  evaporating 
at  a  gentle  heat  until  no  odor  of  camphor  is  detected.  The 
difference  in  weight  will  represent  the  camphor,  while  the 
weight  of  the  residue  evaporated  to  dryness  will  represent  the 
sulphur.  The  subsequent  steps  in  the  scheme  require  no 
explanation. 

In  this  lecture  no  effort  has  been  made  to  enumerate  the 
infinite  list  of  dynamites  which  have  been  proposed  for  use, 
but  merely  to  describe  the  principal  properties  of  a  typical 
powder  under  each  class.  For  purposes  of  reference,  the 
names  and  compositions  of  a  few  of  the  better-known  dyna- 
mites are  given  below. 


CUNCOTTON  BLASTING-POWDERS  AND    DYNAMITES. 

Giant  Powder  No.  I. 

Nitroglycerine. 75.0  parts 

Kieselguhr 24.5      " 

Sodium  carbonate 0.5      " 

Giant  Powder  No.  2. 

Nitroglycerine 40  parts 

Sodium  nitrate 40     " 

Sulphur 6      *  * 

Resin  (powdered) 8     " 

Kieselguhr 8     " 

Dualin. 

Nitroglycerine.    50  parts 

Potassium  nitrate 20     " 

Sawdust 30 


.  i 


Atlas  A. 

Nitroglycerine 75  parts 

Sodium  nitrate    2      " 

Magnesium  carbonate 2      " 

Wood-fibre 21      " 

Atlas  B. 

Nitroglycerine „ 50  parts 

Sodium  nitrate 34     ' l 

Magnesium  carbonate 2      ' ' 

Wood-fibre 14     « ' 

Vulcan  Powder. 

Nitroglycerine 30.0  parts 

Sodium  nitrate 52-5    • " 

Charcoal 10.5      " 

Sulphur 7.0     " 


LECTURES   ON  EXPLOSIVES. 

Judson  Powder  (R.  R.  P.  grade). 

Nitroglycerine 5  parts 

Sodium  nitrate 64     " 

Sulphur 16     " 

Cannel  coal 15      " 

Rendrock. 

Nitroglycerine 40  parts 

Potassium  nitrate 40     " 

Wood-pulp   13      " 

Pitch 7     « 

Hercules  Powder. 

Nitroglycerine 40.00  parts 

Potassium  nitrate 3 1 .00     ' ' 

Potassium  chlorate 3.34     " 

Magnesium  carbonate 10.00     " 

Sugar 15.66     " 

American  Safety  Powder. 

Nitroglycerine 68. 8 1  parts 

Sodium  nitrate 18.35      " 

Wood-pulp 12.84     " 

Carbonite. 

Nitroglycerine 25.0  parts 

Sodium  nitrate 34.0     " 

Sodium  carbonate 0.5      " 

Wood-meal 40.5      " 

Stonite. 

Nitroglycerine 68. o  parts 

Potassium  nitrate  8.O     " 

Kieselguhr 20.0     " 

Wood-meal 4.0 


'* 


GUNCOTTON  BLASTING-POWDERS  AND   DYNAMITES.    $21 
Horsley  Powder. 

Nitroglycerine 72  parts 

Potassium  chlorate 6     " 

Nutgalls I      " 

Wood  charcoal I      " 

Dynamite  de   TrauzL 

Nitroglycerine 75  parts 

Nitrocotton 25      " 

Charcoal 2     " 

Gelignite. 

Nitroglycerine ....   06  parts )   „  . 

XT.  t  Gelatine 65  parts 

Nitrocotton 4  ) 

Sodium  nitrate —    75  parts  \ 

Sodium  carbonate.      I      "      V  Dope 35      " 

Wood-pulp 24     "      } 

Ecrasite. — The  exact  composition  of  this  powder  is  not 
known,  but  it  is  supposed  to  be  a  thin  blasting  gelatine  treated 
with  the  sulphate  or  hydrochlorate  of  ammonium,  or  both, 
together  with  the  picrate  of  ammonium.  For  a  more  exten- 
sive list  of  explosives  reference  may  be  had  to  the  excellent 
compilation  by  Colonel  J.  P.  Cundill,  R.  A.,  H.  M.  Inspector 
of  Explosives. 

For  further  reference  the  following  table  giving  the  per- 
centage of  nitroglycerine  contained  in  various  grades  of  some 
of  the  dynamites  used  in  this  country,  together  with  the  trade 
designations  of  the  several  grades,  is  appended. 


322 


LECTURES   ON  EXPLOSIVES. 


ATLAS. 
(Standard.) 

HERCULEJ 

GIANT. 

Brand. 

Per 

Cent 
N.  G. 

Brand. 

Per 

Cent 
N.  G. 

Brand. 

Per  Cent 

N.  G. 

E                   

2O 

No   4.. 

2O 

Extra  

2O 

K_|_ 

27 

No   4  S     . 

27 

IM 

2O 

D+  

OQ 

No.  38  

•la 

F    F    F    F   . 

2O 

1)+ 

-j-j 

No.  2  

40 

xxx  

27 

c 

&O 

No    2  S 

AC 

No    2  C 

q-i 

C4- 

4  c 

No.  2  SS 

CO 

No    2 

JO 

B   

CQ 

No.  i  

60 

4C 

B-4- 

6O 

No    IX  X 

TC 

New  No    I 

CQ 

A 

7  = 

No    i 

7c 

^ETNA. 

HECLA. 

JUDSON. 

Brand. 

Per 
Cent 
N.  G. 

Brand. 

Per 
Cent 
N.  G. 

Brand. 

Per  Cent 
N.  G. 

No   5 

T  C 

No  3 

20 

R.  R    P    

5  &  under 

No  4 

2O 

No    3X      

27 

F  

10 

No     A  V 

No  2 

on 

F    F     

J  C 

No   •*  B 

27 

No  2V 

qa 

F    F.  F  

20 

No  3 

•JO 

No   i 

4O 

Dbl.  Ex  

27 

No    a  A 

No    iv 

eg 

Trpl    Ex  .    . 

qq 

No  3X 

JJ 

•3C 

No   IX  X  

7s. 

No  2   

4O 

No.  2X  

45 

No  2X  X     .... 

CQ 

No   i  

60 

LECTURE    XVI. 

SMOKELESS    POWDERS. 

EVER  since  Von  Lenk  demonstrated  that  a  perfectly  stable 
product  could  be  obtained  by  nitrating  cotton,  efforts  have 
been  made  to  utilize  this  substance  with  the  view  of  producing 
a  smokeless  explosive  to  be  used  as  a  propellant  in  firearms. 
It  was  very  quickly  proven  that  guncotton  alone,  although 
almost  absolutely  smokeless  when  ignited  or  exploded,  could 
not  be  used  for  this  purpose,  and  it  is  only  comparatively 
recently  that  the  force  of  this  explosive  has  been  successfully 
moderated  and  regulated  so  as  to  admit  of  its  use  in  guns. 
The  more  recent  investigation  and  development  of  smokeless 
powders  dates  from  the  introduction  of  Vieille's  Poudre  B 
in  1886  and  Nobel's  Ballistite  about  the  same  time;  and 
although  all  of  the  so-called  smokeless  powders  may  be  classi- 
fied under  one  or  another  of.  the  classes  of  explosives  already 
enumerated,  on  account  of  the  great  importance  of  this  sub- 
ject it  is  deemed  advisable  to  consider  these  new  substances 
separately. 

Incidentally  it  may  be  stated  that  the  necessity  for  smoke- 
less powder  was  created  by  the  development  of  the  full  power 
of  magazine  small-arms  and  machine  and  rapid-fire  guns,  and 
although  the  new  industry  can  be  said  to  have  but  recently 
emerged  from  the  experimental  stage,  still  the  progress  during 
the  past  five  or  six  years  has  been  so  rapid  and  satisfactory 
that  it  is  now  the  question  of  but  a  very  short  time  before 
the  new  powders  will  surely  supersede  the  old  black  and 
brown  compositions. 

323 


324  LECTURES   ON  EXPLOSIVES. 

Innumerable  substances  have  been  used  in  the  various 
efforts  to  produce  smokeless  powders,  but  at  present  those 
powders  which  seem  to  promise  ultimate  success  may  be 
broadly  divided  in  two  classes,  viz.  : 

(1)  Powders  consisting  essentially  of  insoluble  guncotton 
or    soluble    nitrocotton,    either    alone    or    mixed    in    varying 
proportions,   specially  treated,    or   mixed  with  various  other 
substances  with  the  view  of  regulating  their  explosive  force. 

(2)  Powders  consisting  essentially  of  insoluble  guncotton 
or  soluble  nitrocotton,   either   alone    or    mixed,   to  which  is 
added   nitroglycerine    and  such  other  substances  as  may  be 
necessary  to  regulate  their  force. 

Smokeless  powders  derived  from  picric  acid,  the  picrates, 
ammonium  nitrate,  nitro-derivatives  of  the  aromatic  hydro- 
carbons, have  not  proven  of  sufficient  value  to  merit  more 
than  passing  mention. 

Manufacture  of  Smokeless  Powder. — The  process  of 
manufacture  of  smokeless  powders  is  similar,  whether  they 
belong  to  the  first  or  second  class,  and  does  not  differ  very 
greatly  from  that  followed  in  the  case  of  gelatine  dynamite. 

The  guncotton  or  nitrocotton  is  first  dried  until  it  con- 
tains not  more  than  o.  I  per  cent  of  moisture,  and  is  very 
finely  divided.  The  presence  of  a  greater  amount  of  water 
than  that  specified  or  small  knots  of  nitrocellulose  delays  and 
even  prevents  at  times  the  full  action  of  the  solvent  used  to 
effect  gelatinization.  The  substances  used  as  oxidizers,  mod- 
erators (or  deterrents,  as  they  are  technically  termed),  neutral- 
izers,  etc.,  are  also  finely  pulverized  and  mixed,  dry  or  in  a 
paste,  or  even  dissolved  in  water,  or  a  proportionate  part  of 
the  solvent  to  be  added  after  the  nitrocellulose  is  partially  or 
wholly  gelatinized.  As  a  measure  of  precaution,  in  making 
powders  of  the  second  class  the  nitroglycerine  is  also  dis- 
solved in  a  part  of  the  solvent,  which  serves  to  diminish  very 
greatly  its  explosibility.  The  mixing  is  effected  almost 
entirely  by  means  of  special  machines,  one  of  the  best  being 
the  Werner  kneading-machine. 

This  machine  consists  essentially  of  a  trough  made  in  two 


SMOKELESS  POWDERS.  325 

sections,  the  upper  section  being  rectangular,  while  the  lower 
is  formed  by  two  half-cylinders  placed  side  by  side  and  so 
connected  that  a  ridge  is  formed  along  the  line  of  junction 
which  divides  the  lower  section  into  two  equal  parts. 

In  each  half-cylinder  revolves  a  shaft  fitted  with  helical 
blades,  the  clearance  between  the  cylindrical  surfaces  and  the 
blades  and  between  the  blades  themselves  being  very  small. 
The  shafts  carrying  the  blades  are  made  to  revolve  towards 
each  other  and  at  different  rates  of  speed,  the  number  of 
revolutions  of  one  being  about  double  that  of  the  other,  so 
that  the  material  subjected  to  this  action  is  constantly  changed, 
and  thoroughly  kneaded  and  incorporated. 

The  machine  is  generally  made  of  cast  iron,  and  as  a 
matter  of  precaution  is  often  surrounded  with  a  wrought-iron 
jacket  through  which  water  can  be  made  to  circulate.  To 
empty  the  machine  after  the  incorporation  or  kneading  is 
complete,  the  top  is  removed  and  the  trough  tilted  so  that 
the  paste  is  thrown  out,  or  when  the  trough  is  stationary  the 
shafts  and  blades  are  removed,  and  the  paste  is  taken  out  by 
hand. 

Before  it  is  placed  in  the  machine  the  nitrocellulose  is 
partially  gelatinized  by  pouring  a  portion  of  the  solvent  over 
it,  the  other  substances,  thoroughly  mixed,  are  then  added 
to  the  partially  gelatinized  nitrocellulose,  and  the  entire  mass 
is  put  into  the  machine  and  the  rest  of  the  solvent  added. 

The  machine  is  then  started,  and  during  the  process  of 
kneading  it  is  customary  to  have  every  one  leave  the  build- 
ing, although  the  danger  attending  the  process  is  very  slight. 
The  time  required  to  thoroughly  mix  the  powder  varies  from 
about  four  to  eight  hours,  depending  upon  the  solubility  of 
the  nitrocellulose  and  the  amount  of  solvent  used.  An  ex- 
cess of  solvent  causes  trouble,  due  to  the  difficulty  in  elimi- 
nating it  from  the  resulting  paste,  and  also  often  causes  the 
paste,  when  formed  into  sheets,  cylinders,  etc.,  for  granula- 
tion, to  blister  and  split.  Too  little  solvent,  on  the  other 
hand,  not  only  delays  the  incorporation,  but  is  liable  to  inter- 
fere with  the  perfect  homogeneity  of  the  powder. 


326  LECTURES   ON  EXPLOSIVES. 

The  treatment  of  the  powder  after  it  comes  from  the 
kneading-machines  depends  upon  many  things.  If  the  paste 
contains  too  large  a  percentage  of  the  solvent  it  must  be 
dried  before  it  goes  to  the  press.  During  this  preliminary 
drying  a  "skin"  forms  on  the  powder,  which  materially  in- 
terferes with  the  subsequent  manipulation,  so  that  the  ques- 
tion of  the  proper  amount  of  solvent  to  be  used  is  very 
important.  Until  recently  the  paste  was  rolled  out  into 
sheets  of  varying  thickness  by  passing  it  through  steam- 
heated  rollers.  These  sheets  of  powder  are  then  placed  in  a 
drying-house,  where  the  bulk  of  the  solvent  is  driven  off,  and 
then  rolled  again  to  eliminate  blisters  as  well  as  to  perfect 
the  incorporation. 

By  reducing  the  distance  between  the  rollers  the  resulting 
sheets  are  made  very  thin,  and  should  be  perfectly  transparent 
and  homogeneous.  When  thicker  sheets  are  required,  these 
thin  sheets  are  folded  and  passed  through  rollers  set  at  the 
required  distance.  As  they  come  from  the  rolling-machine 
the  sheets  are  of  the  consistency  of  india-rubber,  and  pass 
next  to  the  cutting-machine.  With  some  of  the  new  powders 
the  sheets  are  "  striated  "  longitudinally  to  facilitate  the  sub- 
sequent granulation.  At  present  the  granulation  of  smoke- 
less powders  is  effected  by  means  of  circular  knives  which 
overlap  each  other,  and  which,  in  the  case  of  powders  rolled 
into  sheets,  cut  the  sheets  into  longitudinal  strips,  while  a 
horizontal  knife  rotating  at  right  angles  to  and  against  a  cutting 
edge  cuts  the  strips  into  cubes.  The  adoption  of  the  cylin- 
drical form  of  grain,  such  as  is  seen  in  cordite,  filite,  etc.,  has 
necessitated  special  forms  of  presses  which  differ  materially 
from  those  used  in  rolling  powder-sheets.  These  machines 
consist  of  a  large  and  very  strong  cylinder,  made  of  cast  iron 
or  steel,  into  which  the  paste  is  placed.  A  piston  entering 
the  cylinder  through  the  head,  which  is  securely  fastened  after 
the  cylinder  is  charged,  is  actuated  by  hydraulic  power,  and 
serves  first  to  compress  the  paste  and  then  to  force  it  out  of  a 
die  attached  to  the  base  of  the  press.  Before  passing  through 
the  die  the  paste  is  generally  forced  through  a  plate  perfo- 


SMOKELESS  POWDERS.  32/ 

rated  with  very  fine  holes  so  as  to  prevent  clogging.  By 
varying  the  diameter  of  the  opening  or  die,  the  same  press 
may  be  used  for  moulding  or  pressing  cylinders,  or  cords  of 
different  sizes.  For  cylinders  of  small  diameters,  such  as 
cordite,  filite,  etc.,  the  cord  or  thread  is  either  reeled  at  once  as 
it  emerges  from  the  press  on  drums,  and  the  drums  are  then 
taken  to  the  drying-house,  where  they  remain  until  all  of  the 
solvent  is  eliminated ;  or  it  is  received  on  a  canvas  belt  which 
passes  over  steam. pipes,  and  is  discharged  into  wire  baskets, 
which  are  subsequently  placed  in  the  drying-house,  until  the 
thread  is  ready  for  granulation.  For  small  arm  powder  the 
threads  are  cut  into  small  cylinders,  while  in  the  case  of 
powder  intended  for  guns  of  large  calibre  the  cylinders  are 
much  longer,  and  even  cut  into  lengths  equal  to  the  length  of 
the  powder-chamber  of  the  gun.  Small-arm  powder  is  dusted 
and  glazed,  as  has  already  been  described  in  the  case  of  ordi- 
nary gunpowder. 

It  would  be  futile  to  undertake  to  describe  minutely  the 
various  processes  of  manufacture  of  the  many  smokeless  pow- 
ders that  have  been  proposed,  and  the  above  description  is 
intended  only  to  give  a  general  idea  of  the  manipulation, 
which  is  subject  to  many  modifications. 

Properties  of  Smokeless  Powders. — The  requisites  for 
a  smokeless  powder  adapted  to  military  purposes  are  approx- 
imate smokelessness ;  stability  under  varying  conditions  of 
climate,  temperature,  and  long  storage;  safety  under  all 
kinds  of  manipulation,  such  as  loading,  rough  handling  in 
transportation,  etc.  ;  freedom  from  noxious  and  irrespirable 
gases  when  exploded ;  it  should  not  develop  excessive  tem- 
peratures nor  erosive  gases  which  are  liable  to  attack  the  sur- 
face of  the  bore  of  the  gun ;  it  should  give  high  and  regular 
velocities  with  uniform  and  moderate  pressures ;  finally,  it 
should  be  safe  from  the  possibility  of  detonation  by  chemical 
or  mechanical  means. 

Although  several  smokeless  powders  have  been  invented 
that  give  more  or  less  satisfactory  results,  it  may  be  safely 


328  LECTURES   ON  EXPLOSIVES. 

asserted  that  no  powder  yet  devised  fulfils  all  of  the  conditions 
enumerated  above. 

The  term  **  smokeless  "  is  relative  only,  and  signifies  that 
the  amount  of  smoke  developed  on  firing  is  so  insignificant 
as  not  to  obscure  either  the  firer  or  the  object  aimed  at,  and 
so  quickly  dissipated  as  to  admit  of  continuous  firing  under 
those  conditions. 

The  question  of  stability  has  been  fully  solved,  and  there 
is  but  little  difficulty  at  present  in  making  a  smokeless  pow- 
der that  will  stand  the  stability  or  heat  test  not  only  at  the  time 
of  manufacture,  but  after  the  lapse  of  several  years,  and  even 
though  the  powder  be  subjected  to  very  considerable  climatic 
and  atmospheric  changes.  The  same  may  be  said  of  the  other 
requisites  enumerated,  except  the  question  of  heat,  the  regu- 
lation of  which  still  causes  no  little  trouble,  and,  up  to  the 
present  time,  has  been  moderated  only  at  the  expense  of 
other  properties  which  do  not  admit  of  the  sacrifice. 

The  color  of  pure  nitrocellulose  powders  is  dull  gray  or 
yellow,  and  when  they  are  pressed  into  sheets  or  ribbons  they 
are  translucent  and  very  homogeneous  in  texture.  Those 
made  of  a  mixture  of  nitrocellulose  and  nitroglycerine  vary  in 
color  from  a  light  yellowish  brown  to  a  dark  opaque  brown, 
while  those  containing  picric  acid  or  the  picrates  possess  the 
characteristic  straw-  or  golden-yellow  color  peculiar  to  those 
substances.  Those  powders  which  are  glazed  present  a  me- 
tallic gray,  black,  or  reddish  appearance,  but  upon  cutting 
through  the  grain  or  washing  off  the  graphite  the  color  pecul- 
iar to  the  composition  of  the  powder  is  seen.  In  texture 
they  are  smooth  and  are  either  of  colloidal  hardness  or  tough 
and  of  the  consistency  of  india-rubber.  As  a  rule  they  are 
insoluble  in  water  and  are  practically  unaffected  by  it. 
Smokeless  powders  are  insensitive  to  the  shock  of  impact  or  to 
the  passage  of  a  bullet  through  them.  They  are  more  difficult 
to  ignite  than  black  powder,  and  in  order  to  develop  their  full 
force  it  is  necessary  to  use  either  a  priming  of  black  powder 
or  stronger  caps.  Although  the  combustion  of  the  new  pow- 
ders is  very  nearly  complete,  and  the  bore  of  the  gun  appears 


SMOKELESS  POWDERS.  329 

perfectly  clean  after  the  firing  of  several  shots,  it  is  neverthe- 
less necessary  to  clean  the  gun  carefully  after  use,  since  traces 
of  nitrogen  compounds  remain  in  the  bore,  which,  combining 
with  the  moisture  of  the  atmosphere,  will  attack  the  surface. 
The  density  of  smokeless  powders  varies  with  the  process  of 
manufacture,  while  the  granulation  is  governed  by  the  calibre 
of  the  gun  in  which  it  is  to  be  used,  the  principal  forms  of 
grains  being  flakes,  ribbons,  sheets,  parallelopipedons,  threads, 
cords,  or  cylinders,  the  last  either  solid,  tubular,  or  multi- 
perforated. 

From  the  records  of  trials  up  to  the  present  time  the  new 
powders  appear  to  possess  ballistic  properties  very  superior  to 
those  of  ordinary  black  or  brown  powder,  much  smaller 
charges  being  required  to  produce  the  same  velocities,  while 
the  chamber-pressures  are  much  lower,  or  for  equal  chamber- 
pressures  the  velocities  are  much  higher  and  uniform. 

Tests  for  Smokeless  Powders.  —  The  several  tests 
already  enumerated  and  described  for  the  determination  of 
the  condition  of  explosives  of  the  nitroglycerine  and  gun- 
cotton  classes  are  equally  applicable  to  smokeless  powders. 
The  time  allowed  for  the  stability  or  heat  test  will  vary 
slightly  according  to  the  composition  of  the  powder,  but  the 
exercise  of  a  little  judgment  will  enable  the  manipulator  to 
decide  upon  the  limit  for  any  particular  powder.  On  account 
of  the  great  hardness  of  many  of  these  powders  it  is  neces- 
sary to  grind  them  before  undertaking  a  test  or  analysis. 
For  this  purpose  any  mill  with  steel  conical  grinding-surfaces 
will  suffice.  The  moisture  should  be  determined  by  drying 
the  ground  powder  at  a  temperature  not  exceeding  40°  C, 
which  will  effectually  eliminate  all  water  as  well  as  traces  of 
solvent  that  may  remain,  and  subsequently  exposing  the 
mass  in  a  desiccator. 

For  a  final  determination  as  to  the  ingredients  and  the 
proportions  which  enter  into  such  a  compound,  it  is  only 
necessary  to  follow  the  outline  of  quantitative  analysis  for 
nitroglycerine  and  guncotton  preparations  already  given  with 
such  modifications  as  may  be  suggested  in  any  particular  case. 


330  LECTURES  ON  EXPLOSIVES. 

U.  S.  Naval  Smokeless  Powder. — The  smokeless  pow- 
der developed  at  the  U.  S.  Naval  Torpedo  Station  to  be  used 
in  guns  of  all  calibres  in  the  U.  S.  Navy  has  given  very  uni- 
form and  satisfactory  results.  It  is  essentially  a  nitrocellu- 
lose powder,  consisting  of  a  mixture  of  insoluble  and  soluble 
nitrocellulose,  to  which  is  added  the  nitrates  of  barium  and 
potassium  and  a  very  small  percentage  of  calcium  carbonate. 
The  proportions  of  these  ingredients  in  the  case  of  powder  for 
the  six-inch  rapid-fire  gun  are  as  follows : 

Mixed  nitrocellulose  (insoluble  and  soluble). ...  80  parts 

Barium  nitrate 15      ' i 

Potassium  nitrate 7.     4     * ' 

Calcium  carbonate I      " 

The  percentage  of  nitrogen  contained  in  the  insoluble  nitro- 
cellulose must  be  13.30  ±  0.15,  while  that  specified  for  the 
soluble  variety  is  11.60  ±  o.  15,  and  the  mean  nitration 
strength  of  the  mixture  must  show  12.75  per  cent  of  nitrogen. 
In  addition  to  the  special  grades  of  nitrocellulose,  as  deter- 
mined by  the  nitrogen  percentages,  the  purity  of  the  nitro- 
celluloses  is  assured  by  imposing  exacting  conditions  as  to 
their  stability,  ignition  temperature,  percentage  of  uncon- 
verted cellulose,  and  other  foreign  substances,  ash,  etc. 

The  solvent  used  in  making  the  powder  consists  of  a  mix- 
ture of 

Ethylic  ether  (sp.  gr.  o.  720) 2  parts 

Ethylic  alcohol  (95$  absolute  by  volume) i      " 

Process  of  Manufacture. — The  relative  amounts  of  the 
insoluble  and  soluble  nitrocellulose  having  been  determined, 
they  are  dried  separately  at  a  temperature  from  38°  to  41°  C. 
until  they  do  not  contain  more  than  o.  \%  of  moisture.  The 
calcium  carbonate  is  also  finely  pulverized  and  dried,  and  is 
added  to  the  mixed  nitrocelluloses  after  they  have  been 
sifted  through  a  i6-mesh  sieve.  The  nitrates  are  next 
weighed  out  and  dissolved  in  hot  water,  and  to  this  solution 


SMOKELESS  POWDERS.  33 r 

is  added  the  mixture  of  nitrocelluloses  and  calcium  carbonate 
with  constant  stirring  until  the  entire  mass  becomes  a  homo- 
geneous paste.  This  pasty  mass  is  next  spread  upon  trays 
and  redried  at  a  temperature  betwen  38°  and  48°  C.,  and 
when  thoroughly  dry  it  is  transferred  to  the  kneading-machine. 
The  ether-alcohol  mixture  is  now  added,  and  the  process  of 
kneading  begun.  It  has  been  found  by  experiment  that  the 
amount  of  solvent  required  to  secure  thorough  incorporation  is 
about  500  c.c.  to  each  500  grammes  of  dried  paste.  To  prevent 
loss  of  solvent  due  to  evaporation,  the  kneading-machine  is 
made  vapor-tight.  The  mixing  or  kneading  is  continued  until 
the  resulting  grayish-yellow  paste  is  absolutely  homogeneous 
so  far  as  can  be  detected  by  the  eye,  which  requires  from 
three  to  four  hours. 

The  paste  is  next  treated  in  a  preliminary  press  (known 
as  the  "  block-press,"  and  is  actuated  by  hydraulic  power), 
where  it  is  pressed  into  a  cylindrical  mass  of  uniform  density 
and  of  such  dimensions  as  to  fit  it  for  the  final  or  powder 
press. 

The  cylindrical  masses  from  the  block-press  are  transferred 
to  the  final  press  whence  they  are  forced  out  of  a  die  under  a 
pressure  of  about  500  pounds  per  square  inch.  As  it  emerges 
from  the  final  press  the  powder  is  in  the  form  of  a  ribbon  or 
sheet,  the  width  and  thickness  of  which  is  determined  by  the 
dimensions  of  the  powder-chamber  of  the  gun  in  which  the 
powder  is  to  be  used.  On  the  inner  surface  of  the  die  are 
ribs  extending  in  the  direction  of  powder  as  it  emerges  from 
the  press,  the  object  of  these  ribs  being  to  score  the  sheets  or 
ribbons  in  the  direction  of  their  length,  so  that  the  powder 
will  yield  uniformly  to  the  pressure  of  the  gases  generated  in 
the  gun  during  the  combustion  of  the  charge.  The  ribbon  or 
sheet  is  next  cut  into  pieces  of  a  width  and  length  corre- 
sponding to  the  chamber  of  the  gun  for  which  it  is  intended, 
the  general  rule  being  that  the  thickness  of  the  grain  (when 
perfectly  dry)  shall  be  fifteen  one-thousandths  (0.015)  of  the 
calibre  of  the  gun,  and  the  length  equal  to  the  length  to  fit 
the  powder-chamber.  Thus,  in  case  of  the  6-inch  rapid-fire 


332  LECTURES  ON  EXPLOSIVES. 

gun  the  thickness  of  the  grain  (or  sheet)  is  0.09  of  an  inch 
and  the  length  32  inches.  The  sheets  are  next  thoroughly 
dried,  first  between  sheets  of  porous  blotting-paper  under 
moderate  pressure  and  at  a  temperature  between  15°  C.  and 
21°.  5  C.  for  three  days,  then  exposed  to  free  circulation  of  the 
air  at  about  21°. 5  C.  for  seven  days,  and  finally  subjected  for 
a  week  or  longer  to  a  temperature  not  exceeding  38°  C.,  un- 
til they  cease  to  lose  weight. 

The  sheets,  when  thoroughly  dried,  are  of  a  uniform  yel- 
lowish-gray color  and  of  the  characteristic  colloidal  consist- 
ency ;  they  possess  a  perfectly  smooth  surface,  and  are  free 
from  internal  blisters  or  cracks.  The  temperature  of  ignition 
of  the  finished  powder  should  not  be  below  172  C.,  and  when 
subjected  to  the  heat  or  stability  test,  it  is  required  to  resist 
exposure  to  a  temperature  of  71°  C.  for  thirty  minutes  with- 
out causing  discoloration  of  the  test-paper. 

Poudre  B. — Poudre  B,  or  Vieille's  powder,  was  devised 
for  use  in  the  French  Lebel  rifle,  Pattern  1886,  and  consisted 
of  a  mixture  of  insoluble  and  soluble  nitrocellulose,  its  exact 
composition  being: 

Insoluble  nitrocellulose 68.2 1  parts 

Soluble  nitrocellulose 29-79      " 

Paraffin    2.00      " 

The  ingredients,  to  which  was  added  about  20  per  cent  of 
water,  were  worked  under  light  runners  until  the  mixture 
became  perfectly  homogeneous,  and  the  paste  was  then  dried 
between  absorbent  material  until  it  contained  about  5  per 
cent  of  water.  It  was  next  broken  up  and  sifted  through 
sieves  of  O.6  mm.  mesh,  dried  again,  and  subjected  to  the 
action  of  a  mixture  of  ether-alcohol,  and  finally  rolled  into 
sheets  of  0.5  mm.  thickness,  which  were  cut  into  squares,  the 
sides  of  which  were  1.5  mm.  in  length. 

The  addition  of  paraffin  serves  to  diminish  its  sensibility 
to  shock  and  to  retard  its  rate  of  combustion. 

Poudre  B  is  claimed  to  be  almost  absolutely  smokeless. 
It  leaves  no  residue  in  the  gun  except  a  few  unconsumed 


SMOKELESS  POWDERS.  333 

grains.  It  is  of  the  consistency  of  hard  rubber,  is  honey- 
yellow  in  color,  and  translucent.  In  the  Lebel  rifle  a  charge 
of  43  grains  produced  a  muzzle  velocity  of  2050  feet  per 
second  with  3350  Ibs.  pressure  per  square  inch.  It  loses  in 
power  during  the  first  two  months  after  manufacture,  neces- 
sitating an  increase  in  the  charge  of  about  10  grains  in  order 
to  produce  the  ballistic  results  given,  but  after  that  time  it 
remains  very  uniform,  and  has  proven  to  be  very  stable. 

Poudre  BN. — This  is  supposed  to  be  a  modification  of 
Vieille's  powder,  an  analysis  of  several  samples  showing  its 
composition  to  be  as  follows : 

Insoluble  nitrocellulose 29. 1 3  parts 

Soluble  nitrocellulose 41.31      " 

Barium  nitrate 19.00      " 

Potassium  nitrate 7.97      " 

Sodium  carbonate 2.03      *  * 

Volatiles 1.43      " 

100.87 

Poudre  BN  differs  from  Vieille's  powder  in  appearance, 
due  to  the  addition  of  the  metallic  salts.  It  is  of  a  light- 
gray  or  drab  color,  perfectly  opaque,  and  rough  to  the  touch. 
The  thin  striated  sheets  into  which  it  is  rolled  are  brittle,  and 
break  readily  along  the  grooves,  the  distance  between  which 
varies  according  to  the  calibre  of  the  gun  in  which  the  powder 
is  to  be  used. 

For  all  guns,  except  small-arms,  the  strips  are  broken 
into  proper  lengths  and  packed  in  canvas  bags.  For  small- 
arms,  the  powder  is  further  granulated,  the  grains  being 
about  1.5  mm.  square  and  about  0.5  mm.  thick. 

The  earlier  samples  of  this  powder  experimented  with  by 
the  U.  S.  Ordnance  Department  presented  no  little  difficulty 
in  securing  proper  ignition,  a  priming  of  two  grains  of  black 
powder  being  required  to  ignite  it  and  develop  its  full  force. 
The  results  of  these  experiments  gave  the  following  ballistic 
results : 


334  LECTURES   ON  EXPLOSIVES. 

With  45  grains  of  BN  powder  a  mean  of  six  shots  (with- 
out priming)  gave  a  velocity  of  1560  f.-s.  and  a  pressure  of 
35,000  pounds. 

In  these  trials  some  little  powder  remained  unconsumed 
in  the  shell  after  firing,  so  a  second  series  of  six  shots  were 
fired  with  a  priming  of  two  grains  of  black  powder,  with 
the  following  result:  velocity,  1703  f.-s.;  pressure,  52,600 
pounds. 

A  second  sample  of  the  same  powder,  but  which  was  in 
some  respects  superior  to  that  just  described,  was  also  tested. 
With  this  powder  ignition  was  prompt,  no  priming  being 
required,  and  the  combustion  appeared  to  be  complete. 

With  40  grains  the  mean  of  five  shots  showed  a  velocity 
of  1762.6  f.-s.  and  a  pressure  of  46,360  pounds;  with  41 
grains  the  mean  of  ten  shots  resulted  in  a  velocity  of  1857 
f.-s.  and  53,470  pounds  pressure;  while  with  42  grains  the 
mean  of  fifteen  shots  gave  the  remarkable  result  of  1904.7 
f.-s.  velocity  and  57,907  pounds  pressure. 

Notwithstanding  the  claims  as  to  the  excellence  of  this 
powder,  grave  doubts  exist  as  to  its  stability,  and  whatever 
modifications  have  been  made  upon  the  original  powder  have 
had  but  one  object  in  view — to  increase  its  stability  under 
extreme  climatic  variations. 

Troisdorf  Powder. —  This  powder,  which  has  been 
adopted  experimentally  by  Germany  as  the  military  service 
powder,  consists  of  a  mixture  of  gelatinized  nitrocellulose 
and  metallic  nitrates.  It  is  made  in  the  ifsual  way,  rolled 
into  sheets,  and  granulated.  For  small  arms  the  thickness  of 
the  sheets  varies  from  0.012  to  0.025  inch,  and  the  grains  are 
square  or  rectangular,  varying  between  0.05  and  0.08  inch  on 
a  side.  The  natural  color  of  the  powder  is  light  gray,  but 
it  is  converted  into  a  metallic  brown  by  being  coated  with 
graphite.  It  is  almost  entirely  smokeless,  and  very  free  from 
dust.  It  does  not  foul  the  gun  even  after  extensive  firing, 
evolves  no  disagreeable  or  noxious  gases,  is  easily  loaded  in 
small-arm  shells,  has  proven  very  stable,  and  seems  to  have 
given  very  satisfactory  ballistic  results. 


SMOKELESS  POWDERS.  335 

Normal  Powder. — This  is  practically  a  nitrocellulose 
compound,  manufactured  by  the  Swedish  Powder  Manufac- 
turing Company,  Landskrona,  Sweden,  and  has  been  adopted 
as  the  service  powder  by  the  Swiss  Army. 

Its  composition  is  as  follows: 

Insoluble  nitrocellulose 96.2  I  parts 

Soluble  nitrocellulose 1 . 80 

Resin i .  99     " 

Normal  powder  is  light  yellow  in  color;  it  is  insensitive 
to  shock  or  friction,  very  stable,  unaffected  by  moisture,  heats 
the  gun  comparatively  little  under  rapid  firing,  and  apparently 
exercises  but  little  injurious  action  upon  the  bore  of  the  gun. 

W.-A.  Powder. — This  powder  is  made  by  the  American 
Smokeless  Powder  Company,  and  has  been  proposed  as  the 
service  powder  for  the  United  States  for  use  in  guns  of  all 
calibres  both  in  the  army  and  navy.  It  is  made  in  several 
grades,  according  to  the  ballistic  conditions  required  to  be 
fulfilled,  and  has  given  excellent  results. 

It  consists  essentially  of  insoluble  guncotton  and  nitro- 
glycerine, with  an  admixture  of  metallic  nitrates  and  an 
organic  substance  used  as  a  deterrent,  or  regulator. 

The  percentage  of  nitroglycerine  varies  according  to  the 
grade  of  powder,  and  may  be  omitted  altogether. 

Only  insoluble  nitrocellulose  of  the  highest  grade  and 
thoroughly  purified  nitroglycerine  are  used,  and  the  process 
of  manufacture  does  not  differ  materially  from  that  described 
in  the  case  of  Cordite,  except  that  the  nitroglycerine  is  dis- 
solved in  a  portion  of  the  acetone,  which  is  the  solvent  used 
to  affect  gelatinization,  before  it  is  added  to  the  guncotton. 
By  thus  dissolving  the  nitroglycerine,  its  explosibility  is 
reduced  to  a  minimum,  and  the  danger  attending  the  sub- 
sequent steps  in  the  process  of  manufacture  is  very  materially 
diminished. 

The  powder  paste  is  pressed  into  solid  threads,  or  tubular 
cords  or  cylinders,  according  to  the  calibre  of  the  gun  in  which 
the  powder  is  to  be  used.  As  the  threads  emerge  from  the 


336  LECTURES  ON"  EXPLOSIVES. 

press  they  are  received  upon  a  canvas  belt  which  passes  over 
steam-heated  pipes,  and  deposited  in  wire  baskets.  The 
larger  cords  or  cylinders  are  cut  into  the  proper  lengths  and 
exposed  upon  trays  in  the  drying-house,  as  already  described. 
The  powder  for  small-arms  is  granulated  by  cutting  the 
threads  into  short  cylinders,  which  are  subsequently  tumbled, 
dusted,  and,  if  not  perfectly  dry,  again  placed  upon  trays  in 
the  drying-house.  Before  being  sent  from  the  factory,  in 
order  to  secure  uniformity,  from  five  to  ten  lots  of  500 
pounds  each  are  mixed  in  a  "  blending-machine,"  after  which 
the  powder  is  stored  in  the  magazines  until  issued. 

Properties  of  W.-A.  Powder.— The  color  of  the  small- 
arm  powder  is  very  light  gray,  the  grains  are  very  uniform 
in  size,  dry  and  hard,  and  cartridges  are  easily  and  uniformly 
loaded  by  machine. 

The  powder  for  larger  guns  is  of  a  yellowish  color,  almost 
translucent,  and  is  almost  as  hard  as  vulcanite.  Irrespective 
of  granulation,  the  powder  is  almost  totally  unaffected  by 
atmospheric  or  climatic  conditions,  powder  submerged  for 
several  weeks  in  a  running  stream  when  removed  and  dried 
not  only  showing  no  sigtis  of  instability,  but  giving  practi- 
cally the  same  ballistic  results  as  powder  just  from  the 
magazine.  The  same  may  be  said  of  powder  exposed  to 
rain,  snow,  and  sun  upon  the  roof  of  a  building  for  over 
three  months.  From  these  and  similar  experiments  there 
seems  little  doubt  that  this  powder  is  well  qualified  to  stand 
the  conditions  of  service. 

W.-A.  powder  is  not  sensitive  to  the  irrlpact  of  bullets, 
and  when  ignited,  even  in  large  quantities,  unless  strongly 
confined,  it  does  not  explode,  but  burns  away.  Like  all 
smokeless  powders,  it  exercises  a  more  deleterious  action 
upon  the  bore  of  the  gun  than  ordinary  gunpowder,  and  the 
question  of  heat  is  not  yet  satisfactorily  settled.  Ballistically 
it  has  given  excellent  results. 

Cordite. — Cordite  is  the  service  smokeless  powder  adopted 
by  Great  Britain  for  use  in  small-arms  and  guns  of  all  calibre. 
Its  composition  is  as  follows: 


SMOKELESS  POWDERS.  337 

Nitroglycerine 58  parts 

Guncotton  37      " 

Mineral  jelly 5      " 

The  conditions  to  be  fulfilled  by  the  nitroglycerine  require 
that,  when  exposed  in  a  desiccator  over  calcium  chloride  for 
1 6  hours  it  shall  not  lose  more  than  0.5  per  cent  of  moist- 
ure ;  that  it  shall  not  show  more  than  o.  I  per  cent  of  alka- 
linity calculated  as  sodium  carbonate ;  and  that  it  shall  stand 
the  heat  or  stability  test  for  15  minutes  when  subjected  to  a 
temperature  of  80°  C.  The  guncotton  is  required  to  contain 
not  more  than  0.6  per  cent  of  mineral  substances,  nor  more 
than  about  4  per  cent  of  soluble  nitrocotton ;  and  that  it  shall 
contain  at  least  12.50  per  cent  of  nitrogen,  as  determined  by 
means  of  the  nitrometer  test. 

The  Manufacture  of  Cordite. — The  dried  guncotton  is 
placed  in  a  brass-lined  box  or  trough  and  the  nitroglycerine 
poured  over  it.  These  two  ingredients  are  thoroughly  mixed 
by  hand  until  the  mass  present  a  homogeneous,  jelly-like  ap- 
pearance. It  is  then  transferred  to  the  kneading-machine 
and  the  solvent — acetone — added,  and  the  mass  is  kneaded  for 
three  and  one-half  hours.  The  machine  is  surrounded  with  a 
water-jacket,  through  which  cold  water  circulates  so  as  to  reg- 
ulate the  heat  and  prevent  evaporation  of  the  acetone.  At 
the  end  of  three  and  one-half  hours  the  top  of  the  machine  is 
opened,  the  mineral  jelly  (vaseline)  added,  and  the  kneading 
is  then  continued  for  three  and  one-half  hours  longer.  From 
this  machine  the  cordite  paste  goes  into  a  preliminary  press, 
where  it  is  freed  as  much  as  possible  from  air  and  formed  into 
a  compact  mould.  The  mould  is  next  transferred  to  the 
final  press,  where  it  is  first  compressed  to  the  required  density 
and  then  forced  out  of  the  press  through  dies  of  varying  sizes, 
depending  upon  the  calibre  of  the  gun  for  which  it  is  intended. 
As  it  emerges  from  the  die,  except  in  the  case  of  the  cylin- 
ders used  in  guns  of  heavy  calibre,  cordite  is  reeled  upon 
sheet-metal  drums,  which  are  mounted  in  a  reeling-machine 
similar  to  those  used  in  reeling  yarn. 


338  LECTURES  ON  EXPLOSIVES. 

The  filled  drums  are  next  taken  to  the  drying-house,  in 
which  a  temperature  of  about  38°  C.  is  maintained  by  means 
of  steam-pipes.  Depending  upon  the  diameter  of  the  cords  or 
cylinders,  it  requires  from  three  to  eight  days  to  thoroughly 
dry  the  powder.  In  order  to  secure  uniform  ballistic  results, 
after  the  powder  is  dried  it  is  blended  for  use  in  small-arms 
as  follows :  The  cordite  from  ten  presses  which  has  been 
wound  upon  "  one-strand  "  reels  is  wound  upon  one  "ten- 
strand  "  reel,  and  then  the  powder  on  six  "  ten-strand  "  reels 
is  transferred  to  a  single  drum,  forming  a  rope  of  sixty  strands, 
which  is  cut  into  short  lengths  forming  small  cylindrical 
grains. 

Cordite  for  use  in  field-guns  is  cut  into  lengths  of  1 2 
inches,  and  for  guns  of  heavier  calibre  into  lengths  of  14 
inches,  and  placed  on  trays  in  the  drying-house  until  perfectly 
dry. 

Properties  of  Cordite. — The  color  of  cordite  varies  from 
light  to  dark  brown,  depending  upon  the  color  of  the  vaseline 
used  in  its  manufacture.  It  has  the  consistency  of  hard 
rubber,  and  preserves  its  elasticity  even  after  long  storage. 
It  generally  retains  a  smell  of  acetone.  Ignited  in  the  open 
air  it  burns  fiercely,  the  cord  pencilling  at  the  ignited  end. 
The  gases  evolved  upon  explosion  are  as  follows: 

CO, 25.40 

CO 37-62 

N : 19-55 

H 17.43 

100.00 

One  gramme  of  Cordite  yields  877  c.c.  of  permanent  gas  and 
produces  1 143  thermal  units. 

The  dimensions  of  the  cords  and  cylinders  used  in  the 
various  guns  are  as  follows : 


SMOKELESS  POWDERS. 


339 


'2-pdr.  B.L. 


Calibre  of  Gun.  Diameter  of  Cordite. 

o".o375 

o  .0500 

o  .0750 

t O.I  OOO 

4*   ^  ^'    '  o  .2000 

6".o  Q.F , o  .3000 

, . . .   o  .4000 

o  .5000 


All  guns  of  heavier  calibre 


The   cylinders   for  heavy  guns  are  tubular.      The  ballistic 
properties  of  cordite  are  shown  in  the  following  table : 


Calibre  of  Gun. 

Charge. 

Weight  of 
Projectile. 

Initial  Velocity, 
Feet  per  Second. 

Pressure, 
Ibs.  per  sq.  in. 

o".303 
12-pdr.  B.L. 
4".?Q.F. 
6".oQ.F. 

30  grs. 
I  Ib.  0.5  oz. 
5  Ibs.  7.0  oz. 
14  Ibs.  3.0  oz. 

215  grs. 
12  Ibs. 
25  Ibs. 
100  Ibs. 

2000  ±   40 
I7IO   ±   2O 
2145    ±   25 
2275 

33,000 
33,000 
33,000 
33,500 

Cordite  has  proven  to  be  a  very  stable  powder  under  very 
extreme  conditions  of  climate,  varying  from  the  extreme 
arctic  cold  of  Canada  to  the  tropical  heat  of  India,  and,  like 
the  great  majority  of  these  compositions,  it  has  resisted  suc- 
cessfully exposure  to  rain,  snow,  and  all  forms  of  moisture 
without  serious  impairment  of  its  ballistic  properties. 

Up  to  the  present  time,  however,  its  effect  upon  the  bore  of 
the  gun  has  proven  a  serious  difficulty.  The  extreme  heat 
developed  by  cordite  upon  explosion,  together  with  the  high 
velocity  imparted  to  the  projectile,  has  served  to  erode  the 
gun  to  such  an  extent  as  to  lead  to  suggestions  of  its  aban- 
donment as  a  service  powder. 

Ballistite. — Since  its  introduction  ballistite  has  under- 
gone considerable  modification,  not  only  in  the  process  of 
manufacture,  but  in  the  proportions  of  the  ingredients,  which 
are  soluble  nitrocellulose  and  nitroglycerine. 


340  LECTURES   ON  EXPLOSIVES. 

At  present  ballistite  consists  of 

Soluble  nitrocellulose 50  parts 

Nitroglycerine  . . . , 50  parts 

to  which  is  added  about  one  per  cent  of  diphenylamine  for 
the  purpose  of  increasing  its  stability. 

As  made  at  present,  the  nitrocellulose  and  nitroglycerine 
in  which  the  diphenylamine  is  dissolved  are  introduced  to- 
gether into  a  vessel  containing  hot  water  and  thoroughly 
mixed  with  constant  stirring  by  means  of  compressed  air. 
When  mixed  as  intimately  as  possible  in  this  way,  the  paste 
is  freed  from  the  bulk  of  the  water  by  means  of  centrifugal 
machines  and  pressing  between  absorbent  material,  and  is 
then  passed  between  rollers  heated  by  steam  to  a  temperature 
of  from  60°  to  90°  C.  By  passing  the  paste  between  these 
rollers  repeatedly,  the  pressure  and  heat  affect  a  very  com- 
plete solution  of  the  nitrocellulose  in  the  nitroglycerine,  and 
at  the  same  time  eliminate  almost  entirely  all  moisture,  so 
that  the  final  sheet  is  very  homogeneous  and  free  from  blis- 
ters. In  color  ballistite  is  very  dark,  almost  black,  and  has 
the  consistency  of  rubber.  Its  average  density  is  1.6.  It  is 
but  little  affected  by  moisture,  is  almost  entirely  smokeless, 
but  is  more  susceptible  to  heat  than  most  of  the  smokeless 
powders.  As  compared  with  other  powders  of  this  class,  it 
has  not  developed  satisfactory  ballistic  properties. 

Although  the  use  of  ballistite  has  been  discontinued  by 
Germany,  it  is  still  the  service  powder  of  Italy,  where  it  is 
made  in  large  quantities  at  the  royal  powder  factory  at  Avi- 
gliano.  The  Italian  powder  is  pressed  into  fine  cords,  similar 
to  cordite,  and  is  known  as  "  Filite"  ;  elsewhere  ballistite  is 
granulated  in  the  form  of  cubical  grains.  Recently  ballistite 
has  been  coated  with  graphite  so  as  to  prevent  the  exudation 
of  nitroglycerine,  to  which  it  has  proven  liable,  and  at  the 
same  time  to  facilitate  the  loading  of  small-arm  ammunition 
by  preventing  the  grains  from  sticking, 

Maxim  Powder. — Excellent  results  have  been  obtained 
from  two  or  three  different  grades  of  smokeless  powder  in- 


SMOKELESS  POWDERS.  341 

vented  by  Mr.  Hiram  S.  Maxim,  especially  from  the  experi- 
mental powder  devised  for  the  12-inch  B.  L.  rifle. 

According  to  the  specifications  of  his  English  letters- 
patent  the  inventor  claims  as  his  object  "the  production  from 
guncotton  of  an  explosive  which  will  be  comparatively  smoke- 
less, or  will  by  its  combustion  produce  much  less  smoke  than 
gunpowder,  and  which,  when  used  in  a  fire-arm,  will  burn 
slowly  as  compared  with  ordinary  guncotton,  and  will  exert  a 
high  pressure  on  the  projectile. 

11  The  process  of  manufacture  differs  somewhat  from  those 
previously  mentioned,  and  is  described  as  follows : 

"  It  [tri-nitrocellulose]  is  first  reduced  to  pulp  in  water  in 
a  rag-engine  or  pulping  or  other  suitable  machine,  and  then 
thoroughly  washed  and  dried.  The  dried  pulp  is  then  placed 
in  a  strong  metal  cylinder  or  chamber,  and  the  air  is  exhausted 
from  the  said  cylinder  or  chamber,  that  is  to  say,  a  vacuum 
or  partial  vacuum  is  created  therein.  The  vaporized  solvent, 
consisting  of  acetone,  either  alone  or  mixed  with  ether  or 
alcohol,  or  with  both  of  these  substances,  is  then  allowed  to 
enter,  or  is  forced  into  the  said  cylinder  or  chamber. 

"  The  air  being  entirely  removed  from  the  interior  of  the 
fibres  of  the  cotton,  the  vaporized  solvent  will  penetrate  to 
the  core  of  every  fibre,  and  the  product  will  be  entirely  free 
from  air-bubbles  and  from  empty  spaces  or  interstices  such  as 
exist  in  ordinary  guncotton." 

After  the  treatment  of  the  guncotton  with  the  vaporized 
solvent  as  above  described,  which  has  the  effect  of  perfectly 
gelatinizing  the  mass,  the  paste  is  either  rolled  into  sheets 
under  considerable  pressure  between  steam-heated  rollers,  or 
is  pressed  through  dies  into  threads,  cords,  or  cylinders — the 
latter,  when  intended  for  guns  of  large  calibre,  being  multi- 
perforated. 

The  flat  grains  are  almost  transparent,  yellowish  in  color, 
and  very  tough.  The  cylindrical  grains  for  use  in  small-arms 
are  whitish  and  opaque  and  somewhat  brittle,  while  the  pow- 
ders of  larger  granulation  are  almost  black,  and  very  hard, 
resembling  very  much  vulcanite. 


342  LECTURES  ON  EXPLOSIVES. 

The  composition  *  of  the  various  grades  differs  between 
wide  limits,  all,  however,  containing  nitrocellulose,  both  insol- 
uble and  soluble,  nitroglycerine,  an  alkaline  carbonate,  and 
castor-oil. 

Analyses  by  Prof.  C.  E.  Munroe  gave  the  following  re- 
sults : 

Flat-grain  powder  for  small-arms — 

Insoluble  nitrocellulose 71. 19 

Soluble  nitrocellulose 8.14 

Nitroglycerine I7-9O 

Sodium  carbonate f ,  2.58 

Volatiles o.  19 

Castor-oil Undetermined 

Cylindrical  grain  for  small-arms — 

Insoluble  nitrocellulose 46.60 

Soluble  nitrocellulose 6. 84 

Nitroglycerine 44.60 

Sodium  carbonate 1 . 70 

Volatiles 0.26 

Castor-oil Undetermined 

Wetteren  Powder. — This  powder  was  introduced  into 
the  Belgian  service  in  1889,  being  manufactured  at  the  royal 
gunpowder  factory  at  Wetteren.  Originally  it  was  a  mixture 
of  nitrocellulose  and  nitroglycerine,  which  were  intimately 
mixed,  amyl  acetate  being  used  as  the  solvent  to  aid  in  the 
incorporation.  The  original  formula  has  been  modified  from 
time  to  time,  and  two  or  more  grades  of  the  powder  are  now 
made,  one  at  least  being  essentially  a  nitrocellulose  com- 
pound. It  is  of  a  dark-brown  color  and  of  the  consistency  of 
india-rubber.  It  is  rolled  into  sheets,  but  its  final  granula- 

*  In  a  recent  paper  Mr.  Maxim  gives  the  composition  of  the  later 
powders,  which  have  proven  very  satisfactory  in  the  U.  S.  government 
tests,  as  follows  : 

Guncotton 90.00 

Nitroglycerine 9.00 

Urea i.oo 


SMOKELESS  POWDERS.  343 

tion  is  very  uneven,  and  the  ballistic  results  have  varied 
between  wide  limits.  It  is  characterized  by  the  peculiarly 
pungent  odor  of  amyl  acetate  (pineapple). 

Leonard  Powder. — This  powder,  which  at  one  time 
seemed  to  promise  excellent  results,  has  failed  to  fulfil  the 
expectations  of  its  inventor.  Its  composition  is  as  follows : 

Nitroglycerine 150  parts 

Insoluble  nitrocellulose 50      " 

Lycopodium   10     ' ' 

Urea 4      " 

Rifleite. — This  powder  is  made  by  the  Smokeless  Powder 
Company,  at  Barwick,  Herts,  and  was  proposed  for  use  in  the 
Lee-Metford  rifle,  o".3O3  cal. 

Its  composition  as  shown  by  analysis  is : 

Insoluble  nitrocellulose 74. 1 6  parts 

Soluble  nitrocellulose 22 .48      ' ' 

Phenyl  amidoazobenzene 2.52      " 

Volatiles 0.84      " 

Rifleite  is  a  flake  powder,  the  grains  being  graphited  to 
protect  them  from  moisture.  The  natural  color  of  the 
powder  is  yellowish,  due  to  the  organic  substance  in  its 
composition. 

Indurite. — Indurite  was  invented  by  Professor  C.  E. 
Munroe,  and  is  made  by  "  colloidizing  "  guncotton  perfectly 
free  from  all  soluble  nitrocotton,  by  means  of  nitrobenzene. 
One  part  of  guncotton  is  dissolved  in  from  one  to  two  parts 
of  nitrobenzene,  the  paste  being  subsequently  run  through 
rollers  and  granulated  or  pressed  through  dies  into  the  form 
of  threads  or  cords.  The  powder  is  then  subjected  to  the 
action  of  hot  water  or  steam,  which  has  the  effect  of  harden- 
ing or  "  indurating  "  it,  whence  the  name  Indurite. 

In  addition  to  the  powders  mentioned  which  have  been 
proposed  for  use  in  military  small-arms  and  guns  of  heavy 
calibre,  and  which  will  serve  to  give  an  idea  of  their  general 


344  LECTURES   ON  EXPLOSIVES. 

characteristics,  manufacture,  and  properties,  there  are  several 
others  intended  almost  exclusively  for  use  in  sporting  rifles 
and  shot-guns.  The  conditions  to  be  fulfilled  by  such 
powders  differ  greatly  from  those  imposed  upon  the  military 
explosive,  and  as  a  general  rule  less  care  is  exercised  in  their 
preparation. 

The  composition  of  some  of  the  better  known  sporting 
smokeless  powders,  as  determined  by  analyses  by  Professor 
C.  E.  Munroe,  are  given  below: 

Schultze  Powder. 

Insoluble  nitrocellulose 32.66 

Soluble  nitrocellulose 27-7i 

Cellulose 1.63 

Barium  nitrate 27.62 

Sodium  nitrate 2.88 

Potassium  nitrate 2.47 

Paraffin 4.20 

Volatiles <*  1.48 

E.  C.  Powder,  No.  I. 

Soluble  nitrocellulose 53-57 

Insoluble  nitrocellulose 1.86 

Cellulose ,..  3.12 

Barium  nitrate 34-26 

Sodium  nitrate 3.67 

Potassium  nitrate  1.48 

Aurin    0.55 

Volatiles 1.17 

S.  K.  Powder. 

Insoluble  nitrocellulose 57.73 

Soluble  nitrocellulose 20.39 

Barium  nitrate 18.08 

Potassium  nitrate 1 .24 

Aurin   i.n 

Volatiles..                             1-43 


SMOKELESS  POWDERS.  345 

5.  R.  Powder. 

Insoluble  nitrocellulose 46.97 

Soluble  nitrocellulose 28.18 

Barium  nitrate l9-97 

Potassium  nitrate 2.35 

Aurin , 1 .06 

Volatiles 1.45 

American  Wood  Powder ',  Grade  C. 

Soluble  nitrolignum 29.25 

Insoluble  nitrolignum 14.06 

Lignin  (charred; 28.08 

Sodium  nitrate 1 5 .27 

Humus 10.32 

Volatiles 3.01 


LECTURE    XVII. 

EXPLOSIVES   OF   THE   SPRENGEL   CLASS. 

IN  1873  Dr.  Hermann  Sprengel  proposed  a  new  class  of 
explosives  which  have  recently  attained  great  prominence  on 
account  of  the  success  that  has  attended  their  manufacture 
and  use. 

The  essential  principle  of  all  explosives  of  the  Sprengel 
class  is  the  admixture  of  an  oxidizing  with  a  combustible  agent 
at  the  time  of,  or  just  before,  being  required  f^r  use,  the  con- 
stituents of  the  mixture  being  themselves  separately  non-explo- 
sive. 

In  1871  Mr.  Silas  R.  Divine  filed  a  caveat  in  the  confi- 
dential archives  of  the  U.  S.  Patent  Office  to  protect  his  claim 
to  the  invention  of  rack-a-rock,  which  is  a  typical  explosive 
of  this  class,  but  he  published  no  patent  until  1880. 

To  Dr.  Sprengel,  therefore,  it  appears,  belongs  the  credit 
of  the  first  publication  of  the  general  underlying  principle  of 
this  important  class  of  explosives. 

In  order  to  realize  and  insure  a  speedy  and  intimate  mix- 
ing of  the  ingredients,  Dr.  Sprengel's  original  plan  was  to  use 
substances  one  or  all  of  which  should  be  in  a  liquid  state. 

Among  the  oxidizing  agents  proposed  were  the  various 
nitrates  and  chlorates,  which  are  solid,  and  nitric  acid,  ni- 
trogen tetroxide,  etc.,  which  are  liquid;  while  among  the 
combustible  substances  were  enumerated  various  nitro  sub- 
stitution products,  carbon  bisulphide,  petroleum,  etc.  All 
explosives  of  this  class  are  powerful,  and  the  majority  of 
them  possess  a  remarkable  degree  of  stability,  requiring  very 

346 


EXPLOSIVES   OF   THE  SPRENGEL    CLASS.  34/ 

strong  detonators  to  provoke  explosion  and  develop  their  full 
force. 

On  account  of  the  danger  attending  the  mixing  of  two 
liquid  ingredients  when  undertaken  by  ordinary  workmen,  this 
subclass  of  Sprengel  explosives  was  very  soon  abandoned  as 
a  possibility  for  general  use,  and  can  hardly  be  said  to  have 
progressed  beyond  the  experimental  stage.  The  same  danger 
precluded  the  general  use  of  those  explosives  made  by  the 
admixture  of  a  solid  and  a  liquid;  while  the  third  class, 
namely,  the  mixture  of  two  solids,  presented  serious  difficulty, 
although  comparatively  safe,  in  that  it  was  found  practically 
impossible  to  secure  uniformity  in  the  resulting  explosive 
without  special  apparatus  with  which  to  mix  the  ingredients 
when  required  for  use. 

In  the  hands  of  practised  and  intelligent  workmen,  how- 
ever, this  class  of  explosives  possesses  many  advantages, 
especially  for  military  purposes. 

Rack-a-Rock. — This  is  one  of  the  best  known  of  these 
mixtures,  and  consists  of  potassium  chlorate  and  mono-nitro- 
benzene (sp.  gr.  1.33).  According  to  General  Abbot,  the 
best  results  are  obtained  when  these  ingredients  are  mixed  in 
the  following  proportions: 

Potassium  chlorate 79  parts 

Mono-nitrobenzene 21      " 

The  ingredients  are  transported  and  stored  separately 
until  required  for  use.  Two  general  methods  of  mixing  are 
pursued,  one  by  dipping  the  chlorate  cartridges  in  a  pail  of 
the  liquid,  the  other  by  placing  the  cartridges  in  a  pan 
arranged  with  cells  to  receive  them,  and  pouring  the  liquid 
over  them. 

In  the  first  case,  the  cartridges  are  placed  in  tiers  in  a  wire 
basket  made  for  the  purpose,  and  the  basket  lowered  into 
the  pail  containing  the  liquid,  subjecting  the  cartridges  to 
immersion  from  3  to  6  seconds,  depending  upon  their  size. 
The  basket  is  then  withdrawn,  the  cartridges  allowed  to  drain 


34-8  LECTURES   ON  EXPLOSIVES. 

for  a  few  moments,  and  at  the  end  of  ten  minutes  they  are 
ready  for  use. 

The  mixing  is  accomplished  more  nearly  according  to  the 
required  proportions  by  means  of  the  saturation  process  than 
by  dipping  as  just  described. 

Each  size  of  cartridge  has  its  corresponding  cell  and  cup, 
into  which  it  is  placed;  and  on  each  cartridge  is  poured 
exactly  one  full  cup  of  the  liquid.  As  soon  as  the  liquid  is 
entirely  absorbed,  the  cartridge  is  removed,  and  after  the 
lapse  of  ten  minutes,  as  before,  it  is  ready  for  use. 

Rack-a-rock  is  a  compact  solid  having  a  specific  gravity 
of  1.7.  According  to  General  Abbot,  "  it  decrepitates  with 
difficulty  when  hammered  on  an  anvil,  but  hardly  ignites  on 
wood."  A  fuse  containing  24  grains  of  fulminating  mercury 
fails  to  explode  a  cartridge  unconfined  or  loosely  confined. 
A  cartridge  struck  by  a  bullet  from  a  Springfield  rifle  flashes, 
but  does  not  detonate.  Ordinary  friction  seems  to  have  little 
tendency  to  cause  explosion.  These  facts  show  it  to  be  quite 
safe  to  handle,  even  when  ready  for  use,  and  it  has  given 
excellent  results  in  rock-blasting  under  General  Newton  at 
Flood  Rock,  240,399  pounds  being  used  on  that  occasion. 

When  tested  within  fifteen  minutes  after  mixing,  samples 
of  this  explosive  have  been  found  quite  sensitive  to  friction 
between  metal  surfaces,  and  even  when  gently  rubbed  in  a 
porcelain  mortar;  while  its  sensitiveness  to  percussion  has 
been  found  to  be  equal  to  that  of  Dynamite  No.  I. 

It  is  very  generally  believed  that  the  fullest  effect  to  be 
derived  from  an  explosive  demands  perfect  explosion,  which 
in  the  case  of  rack-a-rock  would  require  that  all  the  carbon 
present  should  be  oxidized  to  carbonic  acid,  the  hydrogen  to 
water,  and  the  nitrogen  set  free.  Under  this  supposition, 
therefore,  the  following  equation  would  represent  the  explo- 
sion of  rack-a-rock: 


Whence    we    see   that    theoretically   the   proportions   of   the 
ingredients  should  be: 


EXPLOSIVES   OF   THE   SPRENGEL    CLASS.  349 

Potassium  chlorate 89.9  parts 

Mono-nitrobenzene.. 19.1      " 

Accepting,  however,  the  proportions  given  by  General 
Abbot,  the  equation  to  be  assumed  to  represent  the  explosion 
of  rack-a-rock,  when  the  maximum  effect  is  developed,  is 

8KC103  +  2C6H6N02  =  8KC1  +  i  iCO2  +  CO  +  5 H2O  +  N2. 

Examining  this  equation,  we  see  that  instead  of  all  of  the 
carbon  being  oxidized  to  carbonic  acid,  a  small  percentage 
appears  in  the  form  of  carbonic  oxide.  And  what  appears  to 
be  true  in  the  case  of  this  explosive  has  been  found  to  obtain 
in  many  others. 

Hellhoffite. — In  1885  Hellhoff  and  Gruson  patented  a 
new  variety  of  this  class  of  explosives,  which  is  now  known 
to  consist  of  meta-di-nitrobenzene  and  nitric  acid.  By  dis- 
solving the  di-nitrobenzene  in  concentrated  nitric  acid  until 
a  thoroughly  saturated  solution  is  obtained  the  new  explo- 
sive, known  as  hellhoffite,  appears  as  a  dark  red  or  brown 
liquid. 

Approximately  the  proportions  are  as  follows: 

Meta-di-nitrobenzene. 47  parts 

Nitric  acid  (sp.  gr.  1.50) 53      " 

Thus  made  hellhoffite  does  not  appear  to  be  a  new  prod- 
uct, but  merely  a  solution,  and,  if  by  any  chance  the  mixture 
is  not  required  for  immediate  use,  by  adding  water  gradually 
to  the  acid  it  may  be  diluted  to  such  an  extent  that  the 
di-nitrobenzene  will  be  no  longer  held  in  solution,  and  will 
recrystallize.  By  straining  the  mixture  the  crystals  can  be 
separated  and  dried,  and  are  then  ready  to  be  used  again. 
Of  course  the  diluted  acid  cannot  again  be  used  for  making 
the  explosive.  To  develop  the  full  force  of  this  explosive 
requires  the  use  of  a  detonator  twice  as  powerful  as  that  used 
to  explode  ordinary  dynamite. 

Extensive  experiments  were  carried  out  to  prove  the 
superiority  of  hellhoffite  over  all  other  existing  explosives 


35°  LECTURES   ON  EXPLOSIVES. 

both  for  industrial  purposes  and  for  military  use  wherever  a 
perfectly  safe  but  violent  explosive  was  required.  Briefly 
stated,  the  special  advantages  of  this  explosive  are: 

1.  When   detonated  by  the   fulminate  of  mercury,   it   is 
more    powerful    than    nitroglycerine.       Experiments    in    this 
laboratory  show  the  relative  intensities  of  the  two  explosives 
to  be  as  106.17  :  100. 

2.  It  may  be  stored  and  transported  with  perfect  safety  as 
regards  concussion,  since  it  cannot  be  exploded  by  a  blow, 
shock,  or  an  open  flame. 

On  the  other  hand,  however,  it  possesses  certain  dis- 
advantages: 

1.  It  is  a  liquid. 

2.  The  acid  contained  in  it  is  so  volatile  that  it  can  be 
stored  only  in  perfectly  closed  vessels. 

3.  It  is  rendered  completely  inexplosive  by  being  mixed 
with  water,  and  therefore  cannot  be  employed  for  submarine 
work. 

4.  On  account  of  the  action  of  the  acid  oh  the  copper 
cases  of  the  detonators  the  latter  require  particular  treatment 
and  inspection  before  use. 

The  results  of  the  experiments  with  this  explosive  con- 
ducted by  the  German  government  have  not  been  made 
known. 

Oxonite. — Like  hellhofHte,  which  it  very  closely  resenv 
bles  in  appearance,  this  explosive  is  a  simple  solution,  and  is 
made  by  dissolving  picric  acid  in  concentrated  nitric  acid. 

The  action  is  perfectly  quiet  and  is  attended  with  a  slight 
fall  of  temperature  of  the  solution. 

In  experiments  in  this  laboratory  it  was  found  that  the 
proportions  required  to  produce  a  perfectly  saturated  solution 
were  as  follows: 

Picric  acid 54  parts 

Nitric  acid  (sp.  gr.   1.50)   46      " 

These  proportions,  however,  are  subject  to  slight  changes, 
depending  upon  the  strength  of  the  nitric  acid,  and  also  upon 


EXPLOSIVES   OF   THE   SPRENGEL    CLASS.  35 1 

the  condition  of  the  other  ingredient,  whether  merely  pulver- 
ized before  being  added,  or  fused  and  pulverized.  This  last 
condition  was  also  found  to  materially  affect  the  strength  of 
the  resulting  explosive.  For  instance,  assuming  the  standard 
nitroglycerine  to  have  a  value  of  100,  the  relative  intensities 
of  the  oxonite  made  with  picric  acid  not  fused  and  fused  were 
as  64.24  :  69.51. 

Oxonite  is  much  less  powerful  than  hellhoffite,  and  requires 
a  very  powerful  detonator  to  develop  its  full  force;  it  is 
unaffected  by  blows  or  shock,  and  is  entirely  insensitive  to 
friction. 

It  is  generally  conceded  that  this  explosive  is  identical 
with  the  "  A-explosive  "  which  was  surrounded  with  such 
profound  mystery  until  the  occurrence  of  serious  accidents 
during  its  trial  as  a  bursting  charge  for  shells  proved  it  unfit 
for  service.  Other  accidents,  notably  one  in  1884,  have 
caused  oxonite  to  be  regarded  with  suspicion;  but  in  the  case 
of  every  accident  the  cause  can  be  traced  to  the  disregard  of 
the  precaution  against  allowing  the  nitric  acid  to  gain  access 
to  the  contents  of  the  detonator.  When  prepared  com- 
mercially, the  picric  acid,  sometimes  with  the  addition  of  a 
nitrate,  is  packed  in  a  muslin  bag,  which  also  contains  the 
nitric  acid  in  a  hermetically  sealed  glass  tube.  This  tube  is 
broken  by  a  blow  before  the  cartridge  is  required  for  use. 

Panclastite. — This  substance  is  made  by  mixing  liquid 
nitrogen  tetroxide  (N2O,)  with  combustible  substances,  such 
as  the  hydrocarbons,  vegetable,  animal,  and  mineral  oils,  fats 
and  their  derivatives,  but  preferably  with  carbon  disulphide. 
The  inventor,  Mr.  Eugene  Turpin,  proposes  that  the  two 
ingredients  should  be  kept  apart  until  required  for  use,  when 
they  may  be  mixed  in  varying  proportions,  depending  upon 
the  particular  work  to  be  accomplished.  The  proportions 
which  yield  the  most  sensitive  mixture  are  approximately 

Nitrogen  tetroxide 3  volumes 

Carbon  disulphide 2         " 


35  2  LECTURES  ON  EXPLOSIVES. 

The  nitrogen  tetroxide  may  be  prepared : 

1.  By  heating  lead  nitrate: 

2Pb(NOs)2  heat  =  2PbO  +  2NaO4  +  O2. 

2.  By  acting  on  tin  with  nitric  acid; 

5Sn  +  20HNO,  =  H10Sn5O15  +  5H2O  +  ioN2O4 

3.  By  acting  on  nitrosyl  chloride  with  silver  nitrate; 

NOC1  +  AgNO3  =  AgCl  +  N2O4- 

4.  By  the  union  of  oxygen  with  nitrogen  trioxide; 

2N203  +  02^  2N204. 

When  nitrogen  tetroxide  is  made  by  any  of  these  processes 
and  passed  through  a  freezing-mixture,  it  condenses  into 
transparent  crystals,  which  melt  at  —  9°,  and  which  when 
once  melted  do  not  resolidify  until  cooled  to  —30°.  Above 
—  9°  it  forms  a  mobile  liquid,  having  a  specific  gravity  of 
1.451,  which  boils  at  22°. 

The  vapors  from  this  gas  are  of  reddish  color;  possess  a 
pungent,  suffocating  odor  and  an  acid  taste;  they  stain  the 
skin  bright  yellow,  and  are  irrespirable. 

In  making  the  explosive  the  temperature  falls  about  20°. 

Panclastite  ignited  in  the  open  air  burns  with  an  exceed- 
ingly brilliant  flame;  confined  in  a  vessel  and  ignited,  it  burns 
until  the  pressure  of  the  gases  produces  an  explosion.  Ex- 
ploded, however,  by  a  fulminate,  whether  in  the  open  air  or 
confined,  the  explosion  is  complete  and  powerful,  whereas  in 
the  former  case  only  a  portion  of  the  substance  explodes,  the 
remainder  burning  away  quietly. 

The  usual  advantages  are  claimed  for  this  explosive, 
namely,  greater  power  than  dynamite,  perfect  safety  of  the 
constituents  separately,  so  that  they  may  be  stored  and  trans- 
ported without  danger  of  fire  or  explosion,  and  insensitiveness 
of  the  mixture  to  blows  or  friction. 

Romite  or  Romit. — This  explosive  was  invented  by 
M.  Sjoberg,  a  Swedish  engineer,  and  consists  of 


EXPLOSIVES   OF   THE   SPRENGEL    CLASS.  353 

Ammonium  nitrate . .    100  parts 

Nitronaphthaline I      * ' 

Paraffin  oil 2      " 

Potassium  chlorate 7     " 

The  first  three  ingredients  are  intimately  mixed,  and  when 
required  for  use  the  potassium  salt  is  incorporated. 

The  earlier  experiments  with  romite,  especially  tests 
looking  towards  its  adoption  as  a  shell-charge  by  the  Swedish 
artillery,  seemed  to  promise  success,  but  an  investigation 
into  the  cause  of  some  thirteen  explosions  which  occurred  in 
various  places  in  Stockholm  during  a  heated  period  of  1888 
disclosed  the  fact  that  in  eleven  of  the  thirteen  places  romite 
had  been  stored,  and  the  accidents  were  all  attributed  to  the 
"  spontaneous  ignition  "  of  this  explosive.  Since  that  time 
little  or  no  attention  has  been  devoted  to  the  further  develop- 
ment of  this  explosive. 

Practical  Value  of  Sprengel  Explosives. — Although  the 
great  power  of  this  class  of  explosives  is  undoubted,  still 
their  value  as  practical  explosives  for  general  use  is  greatly 
diminished  by  the  fact  that  the  proper  incorporation  of  the 
several  ingredients  (or  even  of  two)  requires  a  higher  degree 
of  intelligence  than  is  ordinarily  found  among  the  practical 
miners.  Moreover,  with  those  explosives  of  this  class  into 
which  nitric  acid  or  carbon  bisulphide  enters  as  one  of  the 
principal  ingredients  the  incorporation  in  confined  spaces, 
such  as  mine-galleries,  etc.,  is  open  to  serious  objection. 

Finally,  with  such  explosives  as  hellhoffite  and  oxonite, 
which  contain  a  large  percentage  of  concentrated  nitric  acid, 
it  is  necessary  to  protect  the  detonator  from  the  action  of  the 
acid  by  thoroughly  coating  it  with  paraffin  or  in  some  other 
efficacious  manner.  Should  the  copper  capsule  containing  the 
detonating  mixture  come  into  contact  with  the  acid,  it  would 
be  quickly  corroded  and  a  premature  explosion  would  almost 
surely  result. 

On  the  other  hand,  the  practical  advantages  of  explosives 
of  this  class  for  military  purposes  are  apparent.  Safe  in 


354  LECTURES   ON  EXPLOSIVES. 

storage  and  transportation,  the  only  source  of  danger  seems 
to  lie  in  proper  manipulation  when  the  explosive  is  required 
for  use,  and  this,  under  the  supervision  of  intelligent  officers, 
can  be  reduced  to  a  minimum.  Control  over  the  power  of  the 
explosive  lies  within  the  hands  of  the  manipulator,  so  that  by 
varying  the  proportions  of  the  ingredients  an  explosive  vary- 
ing in  force  from  that  of  dynamite  to  that  of  ordinary  blasting- 
powder  can  be  prepared  at  will. 


LECTURE    XVIII. 

FULMINATES,  AMIDES,    AND    SIMILAR   COMPOUNDS. 

Chemical  Constitution  of  the  Fulminates. — The  ful- 
minates are  now  regarded  as  metallic  salts  of  a  hypothetical 
fulminic  acid,  or  fulminate  of  hydrogen,  the  formula  for  which 

is  H2C,NaO2. 

This  acid,  which  has  an  intermediate  composition  between 
cyanic  acid,  HCNO,  and  cyanuric  acid,  H3C3N3O3 ,  has  never 
been  obtained  in  a  separate  form,  but  the  fact  of  the  existence 
of  double  fulminates  and  acid  fulminates,  and  the  intimate 
relation  existing  between  the  fulminates  and  the  cyanogen 
compounds,  are  accepted  as  evidence  of  the  existence  of  such 
a  compound. 

Although  the  constitution  of  the  fulminates  is  but  little 
understood,  they  are  generally  considered  iso-nitroso-com- 
pounds,  the  principal  salt  being  that  derived  from  mercury. 

Mercury  Fulminate. — In  the  Philosophical  Transactions 
for  the  year  1800  Howard  stated  that  when  mercury  was 
heated  with  nitric  acid  and  alcohol  an  explosive  compound 
was  formed.  This  substance,  which  was  subsequently  known 
as  Howard's  fulminating  mercury,  appeared  as  a  whitish  salt 
which  crystallized  in  acicular  needles  possessing  a  saline  taste, 
and  which  when  dried  explode  with  extreme  violence  when 
struck  upon  metal,  or  when  a  drop  of  sulphuric  acid  was 
poured  upon  it.  In  the  earlier  attempts  to  substitute  mercury 
fulminate  for  gunpowder  as  a  propelling  agent,  it  was  found 
to  impart  but  low  velocities  to  the  bullets,  while  in  nearly 

355 


356  LECTURES   ON  EXPLOSIVES. 

every  case  it  burst  the  gun.  In  other  words,  the  extreme 
violence  of  its  action  locally,  and  the  great  difficulty  met  with 
in  controlling  this  action,  led  to  its  disuse,  until  the  introduc- 
tion of  percussion-caps  and  primers. 

Quite  a  number  of  methods  have  been  proposed  and  used 
for  the  manufacture  of  mercury  fulminate,  but  the  following 
has  given  the  most  satisfactory  results  when  small  quantities 
are  required  for  experimental  purposes. 

Introduce  into  a  flask,  of  about  300  c.c.  capacity, 

Mercury 10  parts 

Nitric  acid  (sp.  gr.  1.40) 120     " 

and  heat  gently  until  all  the  mercury  is  dissolved,  and  allow 
the  solution  to  cool,  shaking  the  flask  from  time  to  time  to 
secure  homogeneity,  and  then  pour  it  into  a  flask  (2000  c.c. 
capacity)  containing 

Alcohol  (95  per  cent) no  parts 

The  latter  flask  should  be  placed  in  the  open  air  or  under 
a  hood,  so  that  the  fumes  evolved  during  the  reaction  may  be 
rapidly  dissipated,  and  also  at  a  distance  from  any  naked 
light,  or  other  source  of  ignition. 

As  soon  as  the  reaction  is  finished,  fill  the  flask  half  full  of 
filtered  water  and  allow  the  grayish  powder  to  settle.  The 
supernatant  liquid  is  then  poured  off,  and  the  washing  is 
repeated  as  long  as  the  decanted  wash-water  shows  any  traces 
of  acid  reaction.  At  an  atmospheric  temperature  of  15°. 5  C., 
or  above,  no  heating  is  required  to  start  the  reaction;  but 
should  the  temperature  fall  below  60°  (shown  by  the  reaction 
ceasing),  the  flask  should  be  placed  in  a  vessel  containing 
warm  water  until  effervescence  recommences.  During  the 
washing  extreme  care  must  be  taken  that  no  fulminate 
accumulates  on  dishes,  beakers,  or  floors,  or  is  carried  into 
drains,  for  serious  accidents  have  resulted  from  minute  quan- 
tities having  been  spilled  and  having  remained  unnoticed  until 
dry,  when  an  explosion  resulted.  Should  any  be  spilled,  it 


FULMINATES,  AMIDES,  AND  SIMILAR   COMPOUNDS.  357 

should  be  destroyed  at  once  by  means  of  a  solution  of  an 
alkaline  sulphide. 

The  reactions  attending  the  formations  of  mercury  fulmi- 
nate by  this  process  may  be  represented  as  follows: 

1.  3HNO,  +  Hg  =  Hg(N08),  +  HNO,  +  H,O. 

2.  C.H..OH  +  HNO,  =  C.H..NO,  +  H,O. 

3.  C,H..NO,+  HNO,=  H,CaN,O,+  2H,O. 

4.  H.C.N.O.  +  Hg(NO,),  =  HgC,N,0,  +  2HNO,. 

Manufacture  of  Mercury  Fulminate. — Several  methods 
for  making  mercury  fulminate  upon  a  commercial  scale  have 
been  devised,  notably  those  of  Howard,  Liebig,  and  Chevalier, 
all  of  which  possess  greater  or  less  merit.  At  present,  how- 
ever, the  process  of  Chandelon  is  almost  universally  adopted. 
It  consists  essentially  of  dissolving  one  part  of  mercury  in  ten 
parts  of  nitric  acid  having  a  specific  gravity  of  1.40  by  the 
aid  of  gentle  heat,  and  as  soon  as  the  solution  is  complete  and 
has  attained  a  temperature  of  54°  C.,  it  is  poured  into  a  flask 
containing  8.3  parts  of  alcohol  of  specific  gravity  0.83.  In 
most  factories  the  following  rule  of  thumb  holds:  Solution  of 
i  part  of  mercury  in  I  part  of  nitric  acid  (sp.  gr.  1.380)  to  10 
parts  of  alcohol.  The  mercury  is  dissolved  in  a  glass  carboy, 
and  the  solution  poured  into  a  second  carboy  containing  the 
alcohol,  which  is  connected  with  a  series  of  receivers  (Wolff) 
placed  in  a  trough  filled  with  water.  The  last  receiver  is 
connected  with  a  chimney  or  condensing  tower. 

The  reaction  begins  slowly  with  the  development  of 
whitish  fumes,  but  very  soon  becomes  quite  violent,  the  liquid 
boiling  and  evolving  copious  white  vapors  of  carbonic  acid, 
nitric  ether,  acetic  ether,  etc.,  and  finally  the  reddish-brown 
vapor  of  nitric  oxide.  The  vapors  are  condensed  in  the 
receivers,  and  subsequently  distilled  with  slaked  lime,  and 
the  distillate,  which  is  essentially  an  ethereal  solution  con- 
taining a  large  percentage  of  aldehyde,  is  used  again  instead 
of  alcohol  in  making  the  fulminate.  The  reaction  lasts 
between  one  hour  and  a  half  to  two  hours,  at  the  end  of 


358  LECTURES   ON  EXPLOSIVES. 

which  time  the  supernatant  solution  is  decanted  from  the 
fulminate  and  rain-water  substituted.  The  contents  of  the 
carboy  are  next  poured  upon  a  cloth  filter  stretched  upon 
a  wooden  frame  and  washed  repeatedly  until  the  wash-water 
no  longer  shows  the  slightest  traces  of  acidity.  The  filters 
are  then  placed  in  the  open  air,  protected  from  the  direct 
rays  of  the  sun,  and  the  fulminate  allowed  to  dry  until  it 
contains  about  15  per  cent  of  moisture.  It  is  then  packed 
in  papier-mache  boxes  containing  about  8  grammes  each.  In 
some  factories  it  is  stored  entirely  under  water. 

Properties  of  Mercury  Fulminate. — The  color  of  mer- 
cury fulminate  varies  from  almost  pure  white  to  a  dirty  gray, 
depending  upon  the  presence  of  very  fine  unconverted  par- 
ticles of  metallic  mercury  intimately  mixed  in  the  mass.  It 
may  be  purified  by  dissolving  in  boiling-hot  distilled  water, 
allowing  the  solution  to  settle  and  clear,  and  then  decanting 
the  supernatant  liquid,  from  which,  upon  cooling,  the  ful- 
minate crystallizes  out  in  yellowish-white  silky  crystals. 
These  crystals  under  the  microscope  appear  to  consist  of  two 
sets,  the  larger  being  octahedra  with  smaller  orthorhombic 
crystals  entangled  and  twined  along  the  vertical  axis.  Mer- 
cury fulminate  has  a  density  of  4.42  ;  it  has  a  sweetish  acid 
metallic  taste,  and,  like  all  the  compounds  of  mercury,  is 
highly  poisonous.  Its  most  important  property  is  its  extreme 
sensitiveness  to  heat  and  shock  of  every  kind.  Its  heat  of 
formation  (for  one  equivalent  284  grammes)  is  —62,900 
calories.  Its  heat  of  combustion  in  an  inert  atmosphere  is 
-(-116,000  calories  for  constant  volume,  and  +1  H^S00  f°r 
constant  pressure.  This  quantity  of  heat  would  be  sufficient 
to  raise  the  temperature  4200°  C.  Its  heat  of  combustion  in 
air  is  -f-25°>9°°  calories;  the  reaction  attending  its  decom- 
position may  be  represented  as  follows: 

HgC,N,0,  =  Hg  +  2CO  +  N,. 

According  to  this  equation  one  gramme  of  the  fulminate 
should  yield  235.8  c.c.  of  gas.  Berthelot  and  Vieille  have 
verified  this  several  times,  obtaining  234:2  c.c.  Therefore 


FULMINATES,  AMIDES,  AND  SIMILAR    COMPOUNDS.   359 

one  equivalent  (284  grammes)  would  furnish  66.7  litres  of  gas 
at  o°  C.  and  76  cm. 

From  the  above  equation  it  is  seen  that  mercury  fulmi- 
nate, when  detonated,  does  not  give  rise  to  the  formation  of 
any  substance  capable  of  undergoing  a  notable  dissociation, 
consequently  no  gradual  recombination  can  take  place  during 
the  cooling  which  would  retard  the  expansion  of  the  gas  and 
diminish  the  violence  of  the  initial  blow.  This  explains  the 
brusqueness  of  the  explosion,  which  would  be  all  the  more 
violent  but  for  the  condensation  of  the  mercury  vapor. 

Dry  mercury  fulminate  explodes  violently  when  struck, 
compressed,  or  rubbed  between  hard  surfaces;  or  when 
touched  with  concentrated  sulphuric  acid,  or  an  incandescent 
wire,  or  any  ignited  body.  If  it  be  heated  slowly,  it  explodes 
at  152°  C.,  or,  if  heated  rapidly,  at  187°  C.  according  to 
Hess,  and  at  200°  C.  according  to  Leygue  and  Champion. 
Ignited  when  unconfmed  it  detonates  with  only  a  faint  puff, 
but  with  only  a  piece  of  paper  over  it  its  force  is  developed 
in  a  marked  degree.  It  is  readily  exploded  by  blows  of 
metal  upon  metal,  but  with  difficulty  between  wooden  sur- 
faces. It  is  claimed  to  be  inexplosive  when  saturated  with 
water,  or  if  a  particle  of  wet  fulminate  be  exploded,  the 
detonation  is  not  communicated  to  the  rest  of  the  mass. 
There  is  no  doubt  but  that  its  explosibility  is  reduced  by 
moistening,  and  this  property  is  utilized  in  reducing  the 
danger  inherent  in  handling  large  quantities  of  fulminate;  but, 
on  the  other  hand,  explosions  have  been  reported  during  the 
process  of  manufacture  while  the  fulminate  was  still  in  the 
conversion-flask.  Whether  mercury  fulminate  explodes  sym- 
pathetically or  not  is  yet  a  matter  of  doubt.  Attempts  have 
been  made  to  regulate  the  action  of  this  explosive  by  mixing 
it  with  various  substances,  notably  potassium  nitrate  and 
chlorate. 

When  mercury  fulminate  is  mixed  with  potassium  nitrate 
or  chlorate  and  exploded,  the  following  reactions  may  occur: 
5HgC,NA  +  4KNO,  =  5Hg+  8CO2  +  7N2  +  2K2CO3, 
3HgC2N202  +  2KC103  =  3Hg  +  6C02  +  3N2  +  2KC1, 


36O  LECTURES   ON  EXPLOSIVES. 

the  first  of  which  evolves  +227,400  calories  and  the  second 
+258,200  calories,  the  heat  evolved  here  being  double  that 
from  the  pure  fulminate,  but  the  initial  blow  is  tempered 
here  by  the  phenomena  of  dissociation,  due  to  the  carbon 
dioxide,  which  renders  these  explosive  mixtures  less  brusque 
in  their  effects.  The  temperature  is  also  reduced  at  the 
outset  by  the  distribution  of  the  heat  among  the  more  con- 
siderable mass  of  products. 

In  addition  to  these  salts  of  potassium,  other  substances 
are  added  to  the  fulminate  in  making  percussion-caps  and 
detonators,  in  which  industry  it  finds  its  greatest  practical  use. 

Percussion-caps  and  Detonators. — Caps  and  detonators 
are  small  cylinders  made  generally  of  copper  and  filled  with 
an  explosive  composition.  The  size  of  the  cylinder  depends 
upon  the  purpose  for  which  the  cap  or  detonator  is  used, 
caps  used  in  priming  small-arm  ammunition  being  about 
2  mm.  in  length  by  5  mm.  in  diameter,  while  the  ordinary 
blasting-cap  or  detonator  varies  from  16  to  45  mm.  in  length 
and  from  5  to  7  mm.  in  diameter.  The  copper  cylinders  are 
made  in  a  single  piece  by  means  of  a  "  punch-and-die  " 
machine,  and  before  being  charged  are  carefully  cleaned  with 
gasolene,  dried,  and  polished. 

Formerly  various  substances  were  used  in  cap  composi- 
tions, such  as  potassium  nitrate  and  chlorate,  sulphur,  meal 
powder,  phosphorus,  antimony  sulphide,  etc.  Saltpetre, 
sulphur,  and  phosphorus  are  no  longer  used.  For  ordinary 
gunpowder  priming  a  very  good  composition  consists  of: 

Mercury  fulminate 37.5  parts 

Potassium  chlorate   37.5      " 

Antimony  sulphide 25.0     " 

The  mixture  used  in  ordinary  blasting-caps  consists  of: 

Mercury  fulminate . 75  parts 

Potassium  chlorate   25      " 

To  these  mixtures  a  small  percentage  of  ground  glass  is 
sometimes  added,  and  during  the  process  of  mixing,  a  solu- 


FULMINATES,  AMIDES,  AND  SIMILAR    COMPOUNDS.   361 

tion  of  gum  is  used  to  give  greater  coherence  to  the  mass  and 
at  the  same  time  reduce  the  danger. 

The  manipulation  of  mercury  fulminate  is  attended  with 
very  great  danger,  and  the  greatest  caution  is  required  in 
mixing  cap  compositions.  Two  processes  are  followed,  known 
as  the  dry  and  wet.  The  former  requires  special  machines, 
while  in  the  latter  case  the  ingredients  are  moistened  with  a 
solution  of  gum  arabic  in  alcohol  (more  rarely  shellac  or  gum 
benzoe  are  used),  and  then  incorporated  with  a  wooden 
pestle  in  a  wooden  or  porcelain  mortar.  After  incorporation 
the  composition  is  put  into  the  caps  either  wet  or  dry. 
When  charged  wet  the  caps  containing  the  composition  are 
placed  in  the  "  dry-house  "  and  allowed  to  stand  until  the 
moisture  has  been  driven  off,  the  composition  is  then  com- 
pressed and  covered  with  shellac  varnish,  or  a  piece  of  very 
thin  German  silver,  copper-foil,  or  paper.  When  made  for 
use  with  time  fuse  the  mouth  of  the  cap  or  detonator  is  left 
open  to  receive  the  end  of  the  fuse.  In  the  case  of  electric 
fuses  (or  detonators  to  be  fired  by  electricity),  after  the  com- 
position has  been  compressed,  the  open  end  of  the  cylinder  is 
closed  by  means  of  a  plug  made  of  sulphur  and  ground  glass, 
through  which  the  wires  pass  and  extend  for  about  3  or  4  mm. 
The  ends  of  the  wires  are  connected  by  means  of  a  very  fine 
wire  so  as  to  complete  the  circuit,  and  around  this  connecting 
wire  (or  "  bridge  ")  is  wound  a  wisp  of  guncotton. 

Detonators  are  graded  according  to  the  amount  of  fulmi- 
nate they  contain,  and  are  known  commercially  as  single, 
double,  treble,  quadruple,  and  quintuple  force  caps,  the  single- 
force  cap  containing  three  grains  of  fulminate,  and  the  others 
increasing  regularly  by  three  grains. 

The  U.  S.  Navy  detonator  used  in  the  torpedo  service  is 
an  excellent  example  of  an  electric  fuse,  is  more  powerful 
than  any  trade  detonator,  and  differs  somewhat  in  other  par- 
ticulars. It  consists  of  a  copper  case  made  in  two  parts. 
The  lower  part  is  a  No.  38  metallic  cartridge  case,  and  is  i-J- 
inches  long  and  \\  inch  in  diameter.  The  upper  part  is  a 
copper  tube,  open  at  both  ends,  f  inch  long  and  -Jf  inch  in 


362  LECTURES   ON  EXPLOSIVES. 

diameter.  A  T3^-inch  thread  is  cut  on  each  of  these  parts  so 
that  the  upper  part  screws  nicely  on  the  lower.  The  lower 
part  is  filled  with  fulminate  of  mercury  (35  grains)  up  to  the 
lowest  thread  of  the  screw.  The  upper  part  is  fitted  with  a 
plug  of  sulphur  and  glass,  through  which  the  detonator  legs 
pass  to  connect  the  bridge  with  the  wires  leading  to  the 
battery.  When  the  fulminate  is  dry  the  spaces  in  the  lower 
case  and  the  caps  are  filled  with  pulverulent  dry  guncotton, 
and  then  the  parts  are  screwed  together. 

Detonators  are  generally  packed  in  tin  or  varnished  card- 
board boxes  lined  with  felt,  and  the  interstices  filled  with 
sawdust. 

Practically  blasting-caps  may  be  tested  by  fitting  a  cap  in 
a  cork  so  that  the  base  of  the  cap  is  just  flush  with  the  bottom 
of  the  cork,  and  firing  it  on  a  sheet  of  Swedish  iron  supported 
at  its  four  corners.  A  good  cap  should  blow  a  clean  hole 
through  No.  14  A.  W.  G.  iron. 

Silver  Fulminate. — Silver  fulminate  has  a  composition 
similar  to  that  of  the  mercury  salt,  the  acid  hydrogen  of  ful- 
minic  acid  being  replaced  by  silver  instead  of  mercury.  Its 
composition  therefore  would  be  represented  by  the  formula 

AgjC,N,0.. 

Silver  fulminate  may  be   prepared   in    the  laboratory  as 

follows: 

Introduce  into  a  flask,  of  about  300  c.c.  capacity, 

Silver  (granulated) I  part 

Nitric  acid  (sp.  gr.  1 . 308) 2O  parts 

and  shake  gently  until  all  of  the  silver  is  dissolved.  Pour 
the  solution  thus  obtained  into  a  flask  (2000  c.c.  capacity) 
containing 

Alcohol  (87  per  cent)   27  parts 

Bring  the  new  solution  to  a  temperature  of  212°  F.  by 
placing  the  flask  in  a  vessel  containing  boiling  water,  to  which 
additional  water  is  added  as  long  as  the  reaction  continues. 


FULMINATES,  AMIDES,  AND  SIMILAR    COMPOUNDS.  363 

As  soon  as  the  solution  becomes  turbid,  remove  the  flask, 
allow  it  to  cool,  and  add 

Alcohol  (87  per  cent) 27  parts 

and  replace  the  flask  in  boiling  water.  When  the  reaction 
ceases  entirely,  remove  the  flask,  allow  it  to  cool,  and  wash 
the  opaque  white  crystals,  until  the  decanted  wash-water 
shows  no  traces  of  acidity.  This  process,  so  simple  as 
described,  requires  the  greatest  care  and  caution.  All  danger 
of  the  liquid  boiling  over  must  be  eliminated  by  the  use  of 
capacious  vessels.  All  flame  must  be  removed  to  a  distance 
lest  the  vapors  should  take  fire.  The  mixture  must  be  stirred 
carefully,  and,  when  dry,  contact  with  hard  surfaces  must  be 
avoided.  It  is  generally  transferred  by  means  of  paper 
shovels,  and  stored  in  pasteboard  or  paper  boxes,  or,  if  put 
in  glass  bottles,  they  should  not  be  stoppered,  but  the  mouth 
should  be  closed  by  a  piece  of  paper  with  a  sheet  of  rubber 
over  it. 

Prepared  as  above  described,  silver  fulminate  forms  small, 
white,  opaque,  shining  needles,  having  a  strong  bitterish 
metallic  taste,  and  is  very  poisonous.  It  is  but  slightly 
soluble  in  cold  water,  but  dissolves  in  36  parts  of  boiling 
water  and  separates  on  cooling.  It  dissolves  much  more 
freely  in  aqueous  ammonia,  and  is  left  behind  unaltered  as  the 
ammonia  evaporates.  When  exposed  to  white  or  blue  light 
it  gradually  blackens,  giving  off  carbon  dioxide  and  nitrogen, 
and  leaving  a  black  substance  mixed  with  a  small  quantity  of 
the  decomposed  salt.  It  explodes  much  more  violently  than 
the  mercury  salt,  and  under  the  same  conditions.  When  dry, 
it  explodes  at  a  temperature  of  130°  C.  In  a  moist  state  it 
requires  a  much  harder  blow  to  explode  it  than  when  dry, 
but  it  can  be  made  to  explode,  even  under  water,  by  friction 
with  a  glass  rod.  When  well  washed,  and  exposed  to  the 
sun  until  thoroughly  dry,  it  explodes  upon  the  slightest 
touch.  Except  in  the  manufacture  of  detonating  toys,  where 
very  minute  quantities  are  used,  this  salt  is  practically  useless. 


LECTURES   ON  EXPLOSIVES. 

Gold  Fulminate  is  a  violently  explosive  buff  precipitate 
formed  by  adding  ammonia  to  the  terchloride  of  gold. 

Platinum  Fulminate  is  a  violently  explosive  black  precipi- 
tate formed  by  mixing  ammonia  with  a  solution  of  binoxide 
of  platinum  in  dilute  sulphuric  acid. 

Zinc  Fulminate  is  obtained  by  leaving  zinc  and  water  in 
contact  with  mercury  fulminate,  and  allowing  the  solution  to 
evaporate. 

Copper  Fulminate  is  obtained  by  boiling  copper  with  water 
and  mercury  fulminate.  It  appears  in  the  form  of  green 
crystals,  which  explode  violently  when  heated. 

In  addition  to  these  salts  which  are  formed  by  the  replace- 
ment of  all  the  hydrogen  in  the  original  fulminic  acid  by  a 
single  metal,  there  is  another  class  of  fulminates,  which  are 
known  as  double  fulminates,  in  which  one  half  of  the  hydrogen 
is  replaced  by  one  metal  and  one  half  by  another. 

Double  Fulminate  of  Silver  and  Ammonia  is  obtained  by 
dissolving  the  silver  salt  in  warm  ammonia.  Its  composition 
may  be  represented  by  the  formula  Ag(NH4)C3N2Oa.  This 
double  fulminate  is  more  violently  explosive  than  any  of  the 
single  salts,  and  is  exceedingly  dangerous,  even  when  moist. 

Double  Fulminate  of  Silver  and  Potassium,  AgKC2NaO2 ,  is 
obtained  by  adding  potassium  chloride  in  excess  to  the 
fulminate  of  silver. 

In  considering  the  subject  of  the  fulminates,  certain  other 
substances  which,  like  the  salts  of  fulminic  acid,  undergo, 
under  normal  conditions,  a  detonating  explosion  only,  may 
very  properly  be  included. 

Nitrogen  Chloride  or  Chloramide. — From  a  chemical 
standpoint  this  is  the  simplest  example  of  a  detonating  sub- 
stance, as  well  as  one  of  the  most  unstable  of  explosive 
bodies. 

This  substance  was  discovered  in  1811  by  Dulong,  "  who, 
notwithstanding  the  fact  that  h~  lost  one  eye  and  three  fingers 
in  the  preparation  of  this  body,"  yet  continued  the  investiga- 
tion of  the  substance.  The  composition  of  nitrogen  chloride 
had  not  yet  been  accurately,  determined.  It  is  formed  when 


FULMINATES,  AMIDES,  AND  SIMILAR    COMPOUNDS.   365 

chlorine  is  led  into  a  warm  solution  of  sal  ammoniac,  or  when 
a  solution  of  hypochlorous  acid  is  brought  into  contact  with 
ammonia.  From  these  methods  of  formation  it  would 
appear  that  the  chloride  of  nitrogen  is  formed  by  the  replace- 
ment of  the  hydrogen  of  ammonia  by  chlorine,  but  whether 
this  replacement  is  partial  or  complete  is  an  undecided  ques- 
tion. 

If  we  consider  the  replacement  to  take  place  by  degrees, 
then  three  compounds  would  result  according  to  the  amount 
of  chlorine  substituted,  thus: 

NH2C1 monochloramide 

NHCla dichloramide 

NC13 „ trichloramide 

Nitrogen  chloride  may  be  conveniently  prepared  by  invert- 
ing a  bottle  of  chlorine,  perfectly  free  from  greasy  matter, 
over  a  leaden  dish  containing  one  part  of  ammonium  chloride 
in  twelve  parts  of  water.  Great  care  is  required  to  obtain  the 
chlorine  in  a  very  pure  state,  and  the  gas  must  be  dried  before 
it  is  collected  by  passing  it  through  sulphuric  acid. 

Nitrogen  chloride,  or  the  trichloramide,  is  obtained  in  the 
form  of  a  heavy,  yellow,  oily  liquid  (sp.  gr.  1.65),  which 
volatilizes  very  easily  and  yields  a  vapor  of  characteristic  odor 
which  affects  the  eyes.  Heated  to  93°  C.  it  explodes 
violently,  emitting  a  loud  report  and  a  flash  of  light.  Its 
instability  is  due  to  the  feeble  attraction  with  which  its  con- 
stituent elements  are  held  together,  and  the  violence  of  the 
explosion  to  the  sudden  expansion  of  a  small  volume  of  the 
liquid  into  a  large  volume  of  nitrogen  and  chlorine,  and, 
possibly,  hydrogen  chloride.  The  explosion  of  this  substance 
is  at  once  caused  by  contact  with  substances  which  have  an 
attraction  for  chlorine,  such  as  phosphorus  and  arsenic;  the 
oils  cause  its  explosion,  probably  by  virtue  of  their  hydrogen ; 
oil  of  turpentine  explodes  it  with  greater  certainty  than  the 
fixed  oils.  Alkalies  also  decompose  it  violently,  while  acids 
having  no  action  upon  chlorine  are  not  so  liable  to  cause 


366  LECTURES   ON  EXPLOSIVES. 

explosion.  It  has  been  distilled  in  the  open  air  at  71°  C. 
without  explosion. 

The  decomposition  of  the  trichloramide  may  be  repre- 
sented by  the  equation 

2NC13  =  Na  +  3Cl2; 

therefore  one  equivalent  (120.5  grammes)  will  furnish  44.65 
litres  of  gas,  or  one  kilogramme  will  yield  370.5  litres. 

On  account  of  its  constitution  and  properties,  this  sub- 
stance is  of  great  interest  in  the  study  of  explosives,  although 
practically  it  is  perfectly  useless.  It  differs  from  all  other 
explosives  heretofore  considered  in  that  it  contains  no  oxygen, 
and  among  the  products  of  explosion  we  find  only  elementary 
substances.  From  these  facts  it  would  appear  impossible  that 
the  explosion  could  result  from  combustion.  This  phenome- 
non has  been  thoroughly  investigated,  but  only  within  com- 
paratively recent  years  has  any  explanation  been  offered  that 
seemed  satisfactory. 

This  substance  has  already  been  referred  to  under  the 
subject  of  thermo-chemistry. 

Nitrogen  chloride  is  a  remarkable  example  of  the  endo- 
thermous  class,  and  its  extreme  instability  and  explosiveness 
is  explained  as  follows: 

By  observing  the  reaction  which  has  been  assumed  to 
represent  the  decomposition  of  trichloramide,  it  is  seen  that 
the  nitrogen  atoms  unite  with  each  other  to  form  molecules 
of  nitrogen  gas,  and  the  chlorine  atoms  unite  in  a  similar 
manner  to  form  molecules  of  chlorine  gas,  and  the  amount  of 
heat  evolved  by  the  union  of  these  similar  atoms  so  far 
exceeds  the  loss  of  heat  that  attends  the  separation  of  the 
dissimilar  atoms  of  nitrogen  and  chlorine,  that  the  decomposi- 
tion of  this  compound  is  attended  with  the  evolution  of 
38,100  gram-units  of  heat. 

Nitrogen  Iodide  or  lodoafnide.  —  This  body  may  be 
made  by  dissolving  iodine  in  the  least  possible  quantity  of 
alcohol  (95  per  cent)  and  precipitating  it  by  pouring  it  into  a 


FULMINATES,  AMIDES,  AND  SIMILAR   COMPOUNDS.   367 

large  volume  of  water.  The  finely  divided  iodine  thus 
obtained  is  washed  several  times  by  decantation,  and  then 
gently  triturated  in  a  porcelain  mortar  with  a  large  excess  of 
concentrated  ammonia  water  at  o°  C.  for  several  minutes,  and 
the  liquid  poured  off  from  the  subsiding  black  powder.  The 
ammonia  is  replaced  two  or  three  times  by  a  fresh  solution, 
and  the  powder  is  then  transferred  to  a  flask  and  washed 
thoroughly,  first  with  alcohol  (95  per  cent),  then  with  absolute 
alcohol,  and  finally  with  anhydrous  ether,  all  of  these  liquids 
being  artificially  cooled.  After  the  last  washing,  the  ether  is 
decanted  until  only  a  fluid  black  mud  remains,  which  is 
poured  upon  a  filter,  drained  a  few  moments,  and  the  remain- 
ing traces  of  ether  removed  as  vapor  by  means  of  a  current  of 
cold  air. 

On  account  of  its  extreme  sensitiveness,  iodoamide  is  made 
only  for  experimental  purposes,  and  to  avoid  accidents  it  is 
advisable  to  divide  the  filter  with  the  moist  precipitate  ob- 
tained as  above  upon  it  into  small  pieces,  and  expose  them 
to  warm,  dry  air  at  some  distance  from  each  other. 

Iodoamide  is  a  brownish-black  soft  powder,  which  when 
dry  explodes  from  the  slightest  cause,  producing  a  loud 
report,  and  destroying  everything  that  may  be  near  it.  The 
explosion  is  attended  with  a  faint  flash  of  violet  light,  nitro- 
gen being  set  free  as  gas,  and  iodine  in  the  form  of  a  very 
fine  powder.  It  may  be  exploded  by  friction,  even  under 
water,  and  in  the  dry  state  it  detonates  upon  being  touched 
with  a  feather,  or  scratched  with  the  edge  of  a  piece  of  paper. 
When  moist  it  decomposes  slowly  in  contact  with  the  air, 
yielding  nitrogen,  iodic  and  hydriodic  acids,  while  under  water 
it  undergoes  decomposition  in  the  presence  of  a  beam  of  light. 
Like  the  chloride,  the  composition  of  nitrogen  iodide  is  still 
a  question,  Colin  and  Gay-Lussac  holding  that  its  formula 
should  be  NI3 ,  while  others  claim  that  it  contains  more  or 
less  hydrogen. 

Nitrogen  Bromide  or  Bromamide,  whose  composition  is 
probably  analogous  to  that  of  the  chloride,  may  be  formed 
by  decomposing  nitrogen  chloride  with  an  aqueous-solution 


368  LECTURES   ON  EXPLOSIVES. 

of  potassium  bromide.  It  exists  as  a  dense  blackish-red,  very 
volatile  oil,  having  an  odor  like  the  chloride,  and  explodes 
violently  by  contact  with  phosphorus  and  arsenic. 

Nitrogen  Fluoride  or  Fluoramide  is  produced  by  passing 
an  electric  current  through  a  concentrated  solution  of  ammo- 
nium fluoride,  and  is  deposited  as  oily  drops  on  the  negative 
plate.  These  drops  explode  violently  when  brought  into 
contact  with  the  positive  pole,  or  with  glass,  silica,  or  organic 
matter. 

Silver  Amine. — This  substance  was  discovered  by  Berthe- 
lot  nearly  one  hundred  years  ago  by  acting  on  silver  oxide 
with  ammonia. 

The  formula  for  silver  amine  has  been  shown  to  be  Ag8N. 
It  explodes  upon  the  slightest  shock  when  dry,  and  even 
when  wet  it  requires  the  greatest  caution.  It  is  supposed  to 
have  been  the  initial  detonating  agent  in  the  bomb  that  killed 
the  Czar. 

Copper  Amine,  or  Cupricamine. — This  is  the  copper 
compound  similar  to  that  just  described,  and  is  supposed  to 
have  the  composition  Cu6N2.  It  is  formed  by  passing  a  cur- 
rent of  dry  gaseous  ammonia  over  finely  powdered  cupric 
oxide  heated  to  250°  C. ;  water  and  nitrogen  gas  are  evolved, 
and  the  nitride  is  left  as  a  dark  green  powder,  which  when 
heated  to  about  310°  C.  explodes  feebly,  emitting  a  red 
light.  Strong  acids  decompose  it  with  the  evolution  of 
nitrogen. 

Mercury  Amine. — By  passing  dry  ammonia  gas  over  the 
dry  yellow  mercuric  oxide  as  long  as  the  gas  is  absorbed,  and 
then  heating  the  resulting  black-brown  mass  cautiously  at  a 
temperature  not  exceeding  150°  C.  until  water  ceases  to  be 
given  off,  this  substance  is  obtained.  It  detonates  powerfully 
when  struck  or  heated,  and  is  decomposed  by  acids  into  the 
salts  of  ammonium  and  mercury. 

Nitrogen  Sulphide. — This  compound  may  be  obtained 
by  passing  dry  ammonia  gas  through  a  solution  of  sulphur 
dichloride  in  10  or  12  times  its  volume  of  carbon  bisulphide, 
until  the  brown  color  of  the  precipitate  first  formed  disappears. 


FULMINATES,  AMIDES,  AND  SIMILAR    COMPOUNDS.   369 

The  yellow  liquid  is  filtered  from  the  ammonium  chloride 
which  is  produced,  and  allowed  to  evaporate  spontaneously, 
when  the  crystals  of  nitrogen  sulphide  are  formed,  mixed  with 
sulphur.  The  sulphur  is  dissolved  out  by  carbon  bisulphide. 
It  appears  in  the  form  of  golden-yellow  crystals  of  sp.  gr. 
2.22,  and  detonates  powerfully  under  percussion,  but  is  less 
sensitive  than  mercury  fulminate.  It  deflagrates  at  207°  C., 
is  not  affected  by  dry  or  moist  air,  and  has  been  heated  to 
50°  C.,  without  undergoing  change.  It  irritates  the  mucous 
membrane  of  the  nose  and  eyes  painfully,  although  it  pos- 
sesses but  slight  odor.  It  is  an  endothermous  body,  and 
when  decomposed  according  to  the  reaction 


it  evolves  31,900  units  of  heat. 

In  concluding  this  lecture  there  remains  to  be  mentioned 
one  other  class  of  explosive  compounds  whose  mode  of  action 
allies  them  closely  to  those  which  have  just  been  described, 
and  some  of  which  are  so  highly  explosive  that  they  have 
been  proposed  for  use  as  detonating  primers. 

This  class  is  known  as  the  aso-compounds,  and  are  inter- 
mediate between  the  nitro-substitution  and  the  amido-com- 
pounds. 

Diazo-benzene  may  be  considered  as  a  type  of  this  class, 
and  may  be  formed  by  the  indirect  substitution  of  nitrogen 
for  hydrogen  in  benzene.  It  is  a  quite  unstable  substance, 
while  the  nitrate,  which  is  employed  in  the  arts  for  the  manu- 
facture of  dyestuffs,  is  so  explosive  that  it  has  been  proposed 
for  use  as  a  detonating  primer. 

According  to  Berthelot  and  Vieille,  diazo-benzene  nitrate 
is  the  residue  of  two  nitrogenized  bodies  which  have  lost,  the 
one  (nitrous  acid)  its  oxygen,  the  other  (aniline)  a  part  of  its 
hydrogen,  in  the  act  of  combination';  but  a  notable  portion  of 
the  energy  of  these  elements  remains  in  the  residue,  which 
accounts  for  its  explosive  character.  If  preserved  in  dry  air 
out  of  contact  with  the  light,  this  substance  can  be  kept  for 


37°  LECTURES   ON  EXPLOSIVES. 

two  months  and  more,  but  exposed  to  daylight  it  slowly 
changes;  in  moist  air  the  change  is  rapid,  and  in  contact  with 
water  it  is  immediately  decomposed.  When  heated  to  about 
90°  C.  it  detonates  violently ;  heated  slowly  at  a  lower  tem- 
perature it  gradually  decomposes. 

As  a  result  of  his  "  Researches  on  the  Diazo-compounds, " 
P.  Greiss  has  obtained  the  paraditriazobenzene,  which  ex- 
plodes with  extreme  violence,  when  heated  above  its  melt- 
ing-point ;  metamidotriazobenzoic  acid,  which  detonates  when 
heated  in  the  dry  state;  and  metaditriazobenzoic  acid,  which 
when  heated  explodes  with  the  formation  of  a  black  cloud. 

Finally,  silver  hydrazoate,  a  derivative  of  hydrazine — N2H4 
— has  been  very  recently  proposed  as  a  substitute  for  mercury 
fulminate,  but  as  yet  its  properties  are  but  little  understood. 


LECTURE    XIX. 

MANIPULATION,    STORAGE,    AND    TRANSPORTATION    OF   HIGH 

EXPLOSIVES. 

Precautions  to  be  Observed  in  Handling  High  Explo- 
sives.— The  danger  of  careless  handling  of  explosives  has 
already  been  alluded  to,  and  cannot  be  too  strongly  em- 
phasized. Modern  high  explosives  are  justly  claimed  to  be 
safer  to  handle  than  gunpowder,  but  there  are  certain  rules 
which  cannot  be  violated  with  impunity.  The  tremendous 
power  developed  by  the  explosion  of  even  a  few  ounces  of 
these  explosives  renders  the  occurrence  of  small  accidents 
highly  improbable;  and  those  whose  duty  it  is  to  work  with 
them  should  remember  that  no  margin  is  left  for  ignorance, 
carelessness,  or  stupidity.  The  very  safety  of  the  new  explo- 
sives seems  to  lead  those  who  have  had  little  experience  with 
them  into  over-confidence,  and  for  all  who  are  called  upon  to 
deal  with  these  substances  practically,  it  is  well  to  remember 
always  that  "  the  function  of  an  explosive  is  to  explode." 

The  properties  of  the  various  modern  high  explosives  have 
been  enumerated,  and  the  particular  danger  inherent  in  each. 
It  is  therefore  scarcely  necessary  to  add  further  words  of 
caution  with  regard  to  handling  them,  and  preparing  them  for 
use  other  than  to  insist  upon  proper  respect  being  paid  the 
tremendous  power  stored  up  in  these  substances. 

In  making  or  testing  explosives  in  the  laboratory,  be  sure 
that  you  understand  thoroughly  the  several  steps  before  under- 
taking the  experiment,  and  during  the  investigation  use  only 
so  much  as  is  absolutely  necessary  to  attain  your  object, 

37i 


372  LECTURES   ON  EXPLOSIVES. 

Often  one  gramme  will  answer  your  purpose  far  better  than  a 
pound,  and  with  a  correspondingly  smaller  disaster  in  case  of 
accident.  In  using  high  explosives  in  blasting,  or  similar 
practical  operations,  deal  with  only  the  amount  required  for 
immediate  use;  for  instance,  it  is  not  necessary  to  use  more 
than  a  half-cartridge  of  dynamite  in  preparing  a  primer,  there- 
fore do  not  use  a  larger  amount  for  that  purpose.  Do  not 
stand  over  a  box  of  dynamite  or  other  explosive  when  prepar- 
ing a  primer;  and  when  firing  a  charge  be  sure  that  the  supply 
of  explosives  required  for  immediate  use  is  well  protected 
from  the  flying  debris.  Never  carry  detonators  in  the  same 
basket,  cart,  or  wagon  with  the  explosive. 

In  using  detonators  with  explosives  of  the  "  Sprengel 
Class,"  in  which  nitric  acid  enters  as  a  principal  ingredient,  it 
is  absolutely  necessary  to  prevent  the  copper  case  of  the  detonator 
from  coming  into  contact  with  the  acid,  otherwise  a  premature 
explosion  is  sure  to  occur.  To  avoid  such  accidents,  coat  the 
copper  capsule  thoroughly  with  paraffin  by  dipping  it  in  a 
vessel  containing  melted  paraffin,  examining  the  coating  after- 
wards to  be  sure  that  there  is  no  break  in  its  continuity. 

Nitroglycerine  compounds  must  never  be  exposed  to 
shocks  or  violent  compression  between  two  metals.  The 
danger  attending  the  thawing  of  frozen  dynamite  has  been 
alluded  to,  and  the  proper  manner  in  which  the  frozen  sub- 
stance may  be  restored  to  its  plastic  state.  It  is  to  be  noted 
that  while  frozen  dynamite  is  less  sensitive  to  ordinary  shock, 
friction,  and  percussion  than  when  in  the  unfrozen  state,  the 
reverse  is  trde  with  regard  to  explosive  gelatine. 

In  case  of  failure  of  a  charge  to  explode,  or  to  explode  at 
the  proper  time  (^l  hang- fire  "  as  it  is  technically  termed),  do 
not  hurry  in  seeking  for  an  explanation  for  such  failure.  If 
after  waiting  sufficiently  long  (depending  upon  length  of  fuse 
and  other  attending  circumstances)  no  explosion  occurs,  an 
examination  may,  and  generally  should,  be  made.  If  the 
exact  depth  of  the  tamping  be  known,  it  will  generally  suffice 
to  remove  the  tamping  to  within  a  couple  of  inches  of  the 
charge,  insert  a  new  primer,  retamp,  and  repeat  the  attempt 


MANIPULATION,  STORAGE,  AND    TRANSPORTATION.  373 

to  detonate  the  charge.  In  no  case  attempt  to  remove  the 
charge. 

Always  separate  the  tools  used  in  drilling,  boring,  or 
other  preparation  for  a  blast  from  the  explosive  and  detona- 
tors, and  thereby  prevent  the  repetition  of  accidents  so  often 
caused  by  dropping  a  drill,  hatchet,  or  other  tool. 

Never  permit  smoking  in  the  vicinity  of  the  spot  where  a 
blast  is  in  process  of  preparation.  Finally,  before  firing  a 
blast,  be  sure  that  every  one  is  well  beyond  the  danger  zone, 
and  protected  from  flying  debris. 

It  is  not  within  the  scope  of  these  lectures  to  enter  into 
the  theory  of  blasting,  and  those  who  desire  extended  infor- 
mation on  the  subject  must  have  recourse  to  the  various 
treatises  readily  procurable. 

For  such  limited  practical  work  with  high  explosives,  how- 
ever, as  may  be  required  of  an  officer  in  the  ordinary  perform- 
ance of  his  duty,  the  following  suggestions  will  prove  of  value: 

Manipulation  of  High  Explosives  in  Preparing  a 
Charge. — As  already  stated,  dynamite  is  usually  supplied  in 
the  form  of  cartridges,  but  it  may  happen  that  for  special 
reasons,  such  as  for  loading  torpedoes,  submarine'mines,  etc., 
it  is  delivered  and  stored  in  bulk.  In  such  an  event  it  may 
become  necessary  to  prepare  cartridges,  which  may  be  done 
as  follows: 

How  to  Make  a  Dynamite  Cartridge. — The  case  may  be 
made  by  cutting  stiff  brown  manilla  paper  into  rectangular 
sheets  about  five  by  eight  and  one-half  inches,  and  rolling 
these  sheets  around  a  wooden  mandrel  of  the  required 
diameter,  gluing  the  last  fold,  and  turning  in  one  end  of  the 
paper  cylinder  thus  made.  The  case  is  next  dipped  two  or 
three  times  into  melted  paraffin  and  allowed  to  dry.  The 
granulated  dynamite  is  weighed  out  and  introduced  into  the 
case,  and  gently  compressed  by  means  of  a  wooden  tamper, 
and  the  open  end  turned  in  until  the  cartridge  is  required  for 
use. 

How  to  Prepare  a  "Primer"  to  be  Fired  by  Means  of 
a  "Time-fuse." — Dynamite  is  fired  preferably  by  means  of 


374  LECTURES   ON  EXPLOSIVES. 

a  detonating-cap  containing  mercury  fulminate.  The  cart- 
ridge to  which  the  cap  is  attached  is  technically  known  as 
the  primer.  When  electricity  is  not  available,  the  usual 
method  of  firing  a  charge  is  by  means  of  so-called  safety  or 
time  fuses.  One  of  the  best  fuses  of  this  kind  is  made  by 
Messrs.  Bickford  &  Company,  and  consists  of  a  core  of  meal- 
powder  tightly  compressed  and  spun  around  with  yarn  im- 
pregnated with  water-proof  composition. 

Safety-fuses  are  known  as  "  single-"  and  "  double-tape  " 
fuses,  the  former  being  used  ordinarily,  but  the  latter  should 
be  used  when  the  primer  is  to  be  placed  in  damp  places. 

Before  using  a  safety-fuse,  its  rate  of  burning  should  be 
carefully  determined  by  attaching  different  lengths  of  the  fuse 
to  blasting-caps,  and  noting  the  time  necessary  for  the  powder- 
train  to  explode  the  caps.  Having  noted  the  rate  of  burning 
per  foot  of  fuse,  the  next  step  is  to  cut  off  a  length  of  the 
fuse,  which  when  ignited  will  allow  the  operator  ample  time 
to  retire  to  a  place  of  safety  before  the  charge  is  exploded, 
and  to  attach  it  to  the  cap. 

The  cap  is  carefully  examined  to  see  that  no  particles  of 
the  sawdust  in  which  it  is  packed  remain  in  the  open  end, 
and  the  clean,  square-cut  end  of  the  safety-fuse  is  inserted  in 
the  open  end  until  it  is  in  contact  with  the  upper  surface  of 
the  fulminate.  The  fuse  should  fit  the  cap  snugly;  therefore, 
if  it  be  too  large  it  is  pared  down,  or  if  too  small  it  is 
wrapped  with  paper  until  a  close  fit  is  secured.  The  upper 
end  of  the  cap  is  next  tightly  crimped  on  the  fuse,  so  as  to 
secure  the  latter  and  prevent  it  from  becoming  detached.  If 
the  charge  is  to  be  placed  in  a  very  damp  place  or  fired  under 
water,  the  junction  between  the  fuse  and  cap  should  be  made 
water-tight  by  a  coating  of  paraffin,  tar,  shellac,  or  similar 
substance.  The  primer  is  completed  by  attaching  the  cap 
and  fuse  to  the  cartridge.  One  end  of  the  wrapper  is  opened, 
and  with  a  round  stick  slightly  larger  in  diameter  than  the  cap 
open  a  hole  iri  the  centre  of  the  cartridge  and  insert  the  cap, 
at  the  same  time  compressing  the  cartridge  with  the  hand  so 
as  to  bring  the  plastic  dynamite  into  close  contact  with  the 


MANIPULATION,  STORAGE,  AND    TRANSPORTATION.   375 

cap.  The  paper  wrapper  is  then  drawn  around  the  fuse  and 
tied  securely  with  a  string.  The  cap  should  be  inserted  into 
the  dynamite  only  two  thirds  of  its  length,  so  as  to  avoid  the 
possibility  of  the  fuse  setting  fire  to  the  cartridge  before 
igniting  the  fulminate  in  the  cap. 

The  primer  is  placed  preferably  in  the  centre  of  the  charge 
to  be  fired,  and  always  in  contact  with  the  charge.  The 
placing  of  the  charge  depends  upon  circumstances,  and  is 
determined  by  the  object  of  the  blast  in  each  individual  case, 
no  general  rule  being  possible,  save  that  it  should  always  be 
located  so  as  to  produce  the  maximum  effect.  The  location 
of  charges  in  the  work  of  hasty  demolition  will  be  considered 
later. 

How  to  Fire  Dynamite  Cartridges  by  Electricity.— The 
use  of  the  ordinary  time-  or  safety-fuse  for  firing  high  explo- 
sives is  attended  with  two  very  serious  disadvantages: 

1.  The  numerous  failures  to  fire  at  all  and  frequent  cases 
of  "  hang-fire,"  both  of  which,  and  especially  the  latter,  are 
the  cause  of  innumerable  accidents. 

2.  The  practical  impossibility  of  securing  the  simultaneous 
ignition  of  several  charges,  by  means  of  which  double  and  even 
treble  the   effect  is  produced   as  when  the  same  number  of 
charges  are  fired  consecutively. 

Both  of  these  disadvantages  may  be  eliminated  by  using 
electricity  to  ignite  the  primer. 

The  primer  is  prepared  to  be  fired  by  electricity  in  pre- 
cisely the  same  manner  as  already  described  in  the  case  of  the 
time-fuse,  except  that  the  cap  is  entirely  imbedded  in  the 
cartridge,  and  instead  of  tying  the  wrapper  around  the  fuse 
the  fuse-wires  are  doubled  back  and  fastened  to  the  cartridge 
by  two  half-hitches,  which  effectually  prevents  the  cap  from 
being  dislodged.  An  electric  outfit  for  use  with  high  explo- 
sives consists  of  electrical  fuses,  connecting-  or  leading-wires, 
and  an  igniting  apparatus. 

Electrical  Fuses. — Electrical  fuses  may  be  divided  into 
three  classes,  viz. : 


3/6  LECTURES   ON  EXPLOSIVES. 

1.  Loiv  Tension,  for  use  with  strong  electrical  currents  of 
low  potential. 

2.  High  Tension,  for  use  with  condensed   sparks   capable 
of  jumping  a  sensible  air-space. 

3.  Medium  Tension,  specially  designed  for  magneto-elec- 
tric machines  which  generate  electricity  characterized  by    a 
potential  higher  than  the  former  and  lower  than  the  latter. 

Although  the  three  great  classes  are  thus  well  marked,  it 
by  no  means  follows  that  a  given  variety  of  fuse  can  only  be 
ignited  by  a  particular  kind  of  electrical  generator.  While  this 
is  true  for  some  varieties,  others  may  be  fired  by  electricity 
under  any  of  its  characteristic  forms. 

For  example,  the  Abel  magnet-fuse,  although  belonging 
to  the  medium-tension  class,  is  not  unsuited  to  frictional 
machines,  and  it  may  also  be  used  with  voltaic  currents  of 
high  electromotive  force.  As  a  rule,  however,  each  of  the 
three  classes  of  generators  should  be  provided  with  a  fuse 
specially  adapted  to  it. 

The  only  essential  difference  between  the  three  classes 
lies  in  the  manner  of  causing  ignition.  The  low-tension 
variety  usually  acts  by  the  heating  of  a  very  fine  wire  uniting 
the  insulated  conductors  and  imbedded  in  a  suitable  priming. 
The  second  and  third  classes  are  fired  by  the  passage  of  the 
electricity  through  a  small  break  in  the  metallic  circuit  at  this 
point,  the  spark  igniting  a  sensitive  priming;  they  differ  from 
each  other  in  the  chemical  composition  and  the  electrical 
resistance  of  this  priming. 

Every  electrical  fuse  suitable  for  use  with  explosive  com- 
pounds should  have:  1st,  two  insulated  conductors  for  convey- 
ing the  current;  2d,  a  plug  to  receive  and  firmly  hold  an  end 
of  each  near  to,  but  not  touching,  the  other;  3d,  a  small 
priming  suitably  arranged  for  ignition  at  this  point;  and,  4th, 
a  metallic  cap,  containing  a  detonating  charge,  usually  of 
fulminating  mercury. 

The  ordinary  electric  detonator  (or  fuse),  as  well  as  the 
U.  S.  Navy  detonator  used  in  the  torpedo  service,  have  been 


MANIPULATION,  STORAGE,  AND    TRANSPORTATION.   377 

already  described,  and  may  be  taken  as  examples  of  medium- 
tension  fuses,  which  are  used  almost  exclusively  at  present. 

The  ends  of  the  wires  extending  through  the  insulating- 
plug  into  the  cap  to  which  the  "  bridge  "  is  attached  are 
known  as  "  detonator-legs,"  while  the  ends  projecting  out- 
ward are  called  "  fuse-wires."  The  fuse-wires  should  always 
be  well  insulated,  and  not  less  than  two  feet  in  length. 

Connecting-  or  Leading-wires. — The  wires  used  to  con- 
duct the  electricity  from  the  igniting  apparatus  to  the  point 
where  it  is  to  be  applied  are  called  connecting-  or  leading-wires. 
Two  lines  are  used,  one  known  as  the  conducting-wire,  which 
conducts  the  current  to  the  point  of  application;  the  other, 
or  return-wire,  completes  the  circuit  back  to  the  igniter.  Any 
wire  that  is  a  good  conductor  of  electricity  may  be  used;  it  is 
not  necessary  that  it  should  be  insulated,  although  it  is  always 
better  that  it  should  be  so.  If  the  connecting-wires  are 
uninsulated,  care  must  be  taken  that  they  do  not  touch  each 
other  (so  as  to  form  a  short  circuit)  or  the  ground.  It  there- 
fore becomes  necessary  to  attach  such  wires  to  poles  provided 
with  insulators.  For  important  work,  and  especially  when 
used  in  military  operations,  in  which  all  possibility  of  failure 
is  to  be  eliminated  as  far  as  possible,  thoroughly  insulated 
connecting-wires  should  always  be  used.  Everything  con- 
sidered, the  best  connecting-wires  for  electric  igniting  are  a 
perfectly  clean  copper  wire  carefully  covered  with  india-rub- 
ber. For  short  distances  the  cotton-  and  paraffin-covered 
Avires  answer  very  well. 

In  addition  to  these  wires  there  is  another  which  is  still 
more  convenient  for  military  purposes.  It  consists  of  two 
wires  separately  insulated  which  are  encased  in  an  additional 
insulation  so  as  to  form  a  single  wire.  Unless  the  wires  at- 
tached to  the  fuse  are  at  least  two  feet  in  length  it  is  well  to 
join  the  connecting-wires  to  the  fuse-wires  through  the  inter- 
position of  the  two  other  short  wires;  otherwise  the  ends  of 
the  connecting-wires  will  be  constantly  blown  off. 

If  the  blast  is  to  be  a  very  large  or  important  one,  the 
wires  should  be  suspended  from  poles  provided  with  insulators 


378  LECTURES   ON  EXPLOSIVES. 

as  in  the  case  with  uninsulated  wire;  but  for  short  distances 
the  insulated  wires  may  be  stretched  along  the  ground.  For 
all  ordinary  work,  such  as  the  destruction  of  timbers,  iron  or 
steel  rails,  that  would  be  undertaken  in  a  hurried  raid  the 
wires  may  be  most  conveniently  carried  on  a  portable  double 
reel,  so  that  they  can  be  laid  or  gathered  in  with  despatch, 
and  without  danger  of  tangles  and  breaks. 

Igniting  Apparatus. — Various  kinds  of  apparatus  have 
been  devised  for  firing  electrical  fuses,  but  since  the  almost 
universal  adoption  of  medium-tension  fuses  the  use  of 
dynamo-electric  or  magneto-electric  machines  has  superseded 
all  others.  One  of  the  most  serviceable  and  reliable  of  these 
machines  and  one  to  be  particularly  recommended  for  mili- 
tary purposes  is  the  magneto-electric  machine  made  by 
Messrs.  Laflin  and  Rand.  The  Magneto  Machine  No.  3, 
which  has  been  found  to  fulfil  more  of  the  necessary  condi- 
tions of  military  service  than  any  other  form  of  igniter,  is 
encased  in  a  wooden  case  16  X  8  X  5  inches  in  size  and 
weighs  i8£  pounds.  The  external  parts  of  the  machine  con- 
sist of  a  leathern  strap  handle,  two  brass  binding-posts  or  ter- 
minals for  the  leading-wires,  and  a  firing-bar,  which  works 
vertically  through  the  top  of  the  box.  The  internal  arrange- 
ment consists  of  a  Siemens  armature,  which  revolves  between 
soft-iron  prolongations  of  the  cores  of  an  electromagnet. 
The  electricity  thus  generated  is  transformed  by  a  com- 
mutator from  an  alternating  to  a  continuous  current.  The. 
circuit  passes  from  the  commutator-springs  into  the  adjacent 
ends  of  the  windings  of  the  magnet.  The  back-strap  ends 
of  the  windings  of  the  two  halves  of  this  magnet  are  ex- 
tended to  the  terminals  for  the  leading-wires,  and  thence 
to  a  brass  spring  and  collar,  where,  by  platinum  contact- 
points,  they  are  joined  together,  thus  completing  an  interior 
short  circuit  tapped  by  the  fuse  circuit  as  a  shunt.  The 
magnet  is  wrapped  with  1.76  ohms  of  cotton-insulated  copper 
wire  No.  18  B.  W.  G.,  and  the  armature  with  0.92  ohm  of 
No.  21  of  the  same. 

The  novelty  of  the  machine  lies  in  the  mode  of  giving; 


MANIPULATION,  STORAGE,  AND    TRANSPORTATION.  379 

rotation  to  the  Siemens  armature,  and  of  switching  into  the 
fuse  circuit  the  powerful  internal  current  thus  induced.  Both 
objects  are  accomplished  by  the  firing-bar,  which  consists  of 
a  square  brass  rod  14  X  i  X  i  inch,  fitted  with  a  wooden 
handle  at  one  end.  The  other  end  passes  down  into  the  box. 
One  side  is  provided  with  rack  teeth  engaging  in  a  loose 
pinion  fitted  over  the  armature-spindle  prolonged.  A  clutch 
holds  the  pinion  to  the  spindle  when  the  rod  is  descending, 
but  leaves  it  free  when  the  latter  is  raised,  thus  restricting  the 
revolutions  of  the  armature  to  one  direction  only.  When  the 
firing-bar  reaches  its  lowest  position,  it  strikes  the  brass  spring 
forming  part  of  the  interior  circuit,  and  if  in  rapid  motion 
the  shock  breaks  the  circuit  and  thus  shunts  the  current  into 
the  fuse  circuit.  In  passing  from  the  top  to  the  bottom  of 
the  box  the  rod  causes  seven  and  one  half  complete  revolu- 
tions of  the  armature,  and  if  the  movemen-t  be  the  result  of 
a  sudden  and  strong  downward  pressure  this  is  enough  to 
develop  a  powerful  electrical  current. 

To  use  this  igniter  the  ends  of  the  connecting-wires  to  be 
attached  to  the  machine  are  carefully  cleaned,  and  attached 
to  the  terminals  by  unscrewing  the  thumb-screws,  inserting 
the  ends  through  the  holes,  and  tightening  the  screws  until 
they  are  in  firm  contact  with  the  wires.  The  firing-bar  is  then 
withdrawn  to  its  entire  length,  and  when  everything  is  ready 
the  fuse  and  charge  are  ignited  by  forcing  the  bar  home  again 
by  a  swift,  uniform  downward  pressure,  care  being  taken  that 
the  bar  is  kept  strictly  vertical. 

This  form  of  igniter  is  very  compact  and  strong,  and  not 
liable  to  get  out  of  order  except  through  very  rough  usage. 
It  may,  however,  become  temporarily  deranged  through  two 
causes: 

First. — Dust  or  some  foreign  substance  may  find  its  way 
between  the  platinum  contact-points.  By  removing  the 
screws  that  hold  it  in  place  the  rear  of  the  case  may  be 
removed  and  the  trouble  remedied  by  using  a  piece  of  fine 
emery-cloth. 

Second. — Trouble  may  arise  from  the  surface  of  the  com- 


LECTURES   ON  EXPLOSIVES. 

mutator  becoming  tarnished.  In  order  to  cleanse  it  remove 
the  rear  of  the  case  as  before,  and  also  the  small  pin  near  the 
lower  end  of  the  rack,  and  then  withdraw  the  rack  from  the 
case.  The  works  of  the  machine,  with  the  shelf  upon  which 
chey  rest,  are  next  partially  removed  from  the  case,  and  the 
springs  which  press  upon  the  commutator  and  the  yoke  which 
holds  in  place  the  spindle  upon  which  the  commutator 
revolves  are  disconnected.  The  commutator  may  then  be 
cleaned  with  a  piece  of  emery-cloth. 

Proper  attention  to  these  details  and  careful  preparation 
of  tho  wires  and  fuses  save  a  vast  deal  of  trouble,  and  cannot 
be  too  strongly  insisted  upon  where  success  is  absolutely 
necessary  and  time  is  to  be  saved. 

Precautions  to  be  Observed  in  Firing  High  Explosives 
by  Electricity. — In  order  to  reap  the  full  benefit  to  be 
derived  from  the  application  of  electricity  to  firing  high  explo- 
sives close  attention  must  be  devoted  to  certain  details, 
especially  to  the  preparation  of  the  wires.  As  before  stated, 
the  fuse-wires  should  be  at  least  two  feet  long,  and  if  of  lesser 
length  they  should  be  connected  with  the  leading-wires 
through  a  coupling  of  two  short  wires,  otherwise  the  ends  of 
the  leading-wires  will  be  constantly  blown  off.  If  practicable, 
whenever  the  primer  is  to  be  placed  in  a  bore-hole,  the  fuse- 
wires  should  be  long  enough  to  extend  at  least  six  or  eight 
inches  outside  of  the  hole.  The  ends  of  the  fuse-wires  are 
prepared  to  be  connected  with  the  leading-wires  by  paring  off 
two  or  three  inches  of  the  insulation  and  cleaning  the  bare 
ends  of  the  wire  with  a  piece  of  sand-paper.  If  the  leading- 
wires  be  insulated,  the  ends  are  prepared  in  the  same 
manner;  if  they  be  uninsulated,  the  ends  are  thoroughly 
cleaned  by  being  rubbed  or  scraped  so  as  to  remove  any  dirt, 
rust,  or  other  substance  that  might  form  a  coating  on  their 
surface. 

The  fuse-wires  are  joined  to  the  leading-wires  by  bending 
back  the  ends  of  the  latter  so  as  to  form  a  hook  and  then 
twisting  the  ends  of  the  former  snugly  around  them.  If  the 
ground  be  very  damp,  or  if  the  charge  is  to  be  placed  under 


MANIPULATION,  STORAGE,  AND    TRANSPORTATION.   381 

water,  it  is  necessary  to  use  insulated  leading-wires,  and  also 
to  protect  the  junctions  of  the  leading-  and  fuse-wires.  This 
may  be  conveniently  done  by  slipping  pieces  of  rubber  tubing 
over  the  ends  of  the  leading-wires,  and  as  soon  as  the  junc- 
tions are  made,  sliding  the  tubing  over  the  exposed  places 
and  tying  the  ends  tightly  with  twine. 

Never  connect  the  fuse-wires  witJi  the  leading-wires  until 
absolutely  sure  tJiat  at  least  one  of  the  opposite  ends  of  the  latter 
is  disconnected  from  the  igniting'  apparatus. 

The  fuse-  and  leading-wires  having  been  connected,  the 
primer  and  charge  placed  in  position,  and  the  operator  having 
retired  into  a  place  of  safety,  then,  and  not  until  then,  should 
the  terminals  of  the  leading-wires  be  connected  with  the  igniting 
apparatus. 

The  ends  of  the  leading-wrires  are  cleaned,  and  attached 
to  the  brass  binding-posts  by  unscrewing  the  thumbscrews, 
inserting  the  ends  in  the  holes,  and  tightening  the  screws 
until  they  are  in  firm  contact  with  the  wires. 

To  fire  the  charge,  the  firing-bar  of  the  apparatus  is  with- 
drawn to  its  full  length,  and  then  forced  home  again  by  a 
swift,  uniform,  downward  pressure,  care  being  taken  that  the 
bar  is  kept  strictly  vertical  so  as  not  to  be  bent.  With  proper 
attention  to  details,  it  is  possible  to  fire  fifteen  charges  in  the 
same  circuit  simultaneously. 

Precautions  to  be  Observed  in  Loading  Shell  and  Tor- 
pedoes.— Torpedoes  and  shell  are  charged  as  follows:  The 
loading  should  always  be  done  in  light  wooden  buildings,  well 
ventilated;  the  floor  should  be  frequently  swept,  and  the 
sweepings,  including  paper  wrappings,  should  be  burned  in 
the  open  air.  Extremes  of  heat  and  cold  are  unfavorable 
conditions.  No  acids  or  alkalies  should  be  allowed  near  the 
explosives,  and  above  all  no  fuses.  The  latter  are  as  danger- 
ous as  matches  in  a  powder-magazine. 

No  unnecessary  fire  must  be  permitted  in  the  vicinity. 
It  is  true  that  small  quantities  of  these  high  explosives  ignite 
by  a  spark  or  flame,  and  burn  away  harmlessly;  but  the  result 
is  different  if  the  quantity  be  large  enough  to  give  time  for 


382  LECTURES   ON  EXPLOSIVES. 

the  heat  of  the  burning  portion  to  raise  the  rest  of  the  mass 
to  the  temperature  of  explosion.  Disastrous  accidents  have 
been  traced  to  this  peculiarity  as  a  probable  cause;  and  it  is 
therefore  well  to  have  no  larger  supply  in  the  loading-room 
than  is  necessary  for  immediate  use. 

Particular  care  must  be  taken  in  loading  torpedoes  and 
shell  that  none  of  the  material  remains  in  the  screw-threads. 
The  funnels  are  made  long  enough  to  project  entirely  through 
the  loading-holes;  but  examination  in  every  case  should  be 
made  to  see  that  both  the  male  and  female  screw  are  free  from 
particles  of  dynamite,  before  attempting  to  close  the  can  or 
torpedo.  That  none  of  the  powder  should  be  scattered  about 
the  floor  or  among  the  tools,  is  self-evident. 

Any  exudation  of  free  nitroglycerine  must  be  carefully 
avoided.  It  is  not  likely  to  occur  at  ordinary  temperatures; 
but  as  with  other  oils,  warmth  promotes  fluidity.  For  this 
reason  a  loaded  torpedo  must  never  be  left  exposed  to  a  hot 
sun ;  the  heat  of  the  confined  air  rises  to  an  extraordinary 
degree  under  such  circumstances  in  a  few  minutes.  Accord- 
ingly, the  torpedo  must  be  placed  in  the  shade  ;  or,  if  this  be 
impossible,  it  must  be  covered  with  blankets  kept  wet  by 
frequent  additions  of  water. 

Nitroglycerine  which  has  exuded  from  its  absorbent 
recovers  all  its  dangerous  properties,  and  this  rule  is  there- 
fore imperative. 

If  there  be  any  chance  that  the  temperature  of  the  sea- 
water  may  fall  below  45°  F.,  care  must  be  taken  in  loading 
the  torpedo,  and  especially  in  priming  the  fuse-can,  that  the 
dynamite  is  left  loose  without  any  packing.  In  this  state  it  is 
certain  to  detonate  when  the  fuse  explodes;  while  if  packed 
solid,  as  in  cartridges,  a  failure  might  occur. 

Special  care  is  requisite  that  the  fuses  are  deeply  embedded 
in  the  priming  charge  of  the  fuse-can. 

Storage  of  High  Explosives. — If  it  can  be  avoided,  gun- 
powder and  high  explosives  should  never  be  stored  in  the 
same  magazine;  nor  for  obvious  reasons  should  high  explo- 


MANIPULATION,  STORAGE,  AND    TRANSPORTATION.   383 

sives  be  stored  within  the  main  work  of  a  fortification,  nor 
within  the  radius  of  500  yards  of  other  buildings. 

If  any  considerable  quantity  of  these  explosives  is  to  be 
stored,  it  is  advisable  to  erect  a  special  magazine  for  the 
purpose  in  the  most  unfrequented  place,  and  to  mark  it 
plainly  so  that  its  dangerous  character  may  be  recognized. 

It  is  also  advisable  to  store  not  more  than  1200  or  1500 
pounds  of  high  explosives  in  a  single  magazine.  Such  an 
amount  of  explosives  may  be  stored  in  a  magazine  14  feet 
long  by  9  feet  wide  by  9  feet  high,  interior  dimensions. 

The  magazine  should  be  as  light  as  possible,  consistent 
with  the  necessary  strength.  The  use  of  wood  in  construction 
is  recommended  in  preference  to  any  other  material,  although 
corrugated  iron  or  steel  possesses  the  qualities  of  strength  and 
lightness.  The  building  should  be  ceiled  throughout  with  a 
space  between  the  inner  ceiling  and  outer  sheathing  of  not 
less  than  six  inches.  This  space  should  extend  overhead  and 
under  the  floor  as  well  as  around  the  sides,  and  should  be 
packed  with  sawdust  or  any  form  of  cellulose.  The  use  of 
cellulose  sheathing-boards  on  the  interior  is  also  recom- 
mended. 

The  magazine  should  be  closed  with  a  tight-fitting  door 
of  double  thickness.  The  magazine  should  be  fitted  with 
racks  or  shelves  to  receive  the  boxes  and  cases  of  explosives 
arranged  along  the  sides,  leaving  a  broad  passageway,  which 
should  be  kept  scrupulously  clean. 

Every  box  or  case  of  high  explosives  should  be  opened  as 
soon  as  it  is  received  at  the  post,  and  the  condition  of  its 
contents  examined,  and  noted  in  the  magazine-book.  If 
found  to  be  in  good  order,  strips  of  blue  litmus  paper  should 
be  placed  in  each  box,  and  the  top  replaced  and  secured  by 
screws.  Before  a  box  is  placed  in  the  magazine  it  should  be 
given  two  thick  coats  of  paint  or  shellac,  to  protect  the  con- 
tents  Irom  moisture,  and  should  be  properly  marked  as  to 
the  kind  of  explosive  they  contain,  condition  when  examined, 
and  date  of  examination.  The  boxes  should  be  examined  at 


384  LECTURES   ON  EXPLOSIVES. 

least  once  a  month,  the  old  litmus  paper  replaced  by  fresh 
strips,  and  the  boxes  turned  over. 

The  floor  immediately  under  the  boxes  should  be  covered 
with  clean  white  sawdust  to  absorb  any  nitroglycerine  which 
may  exude,  and  in  case  of  leakage  the  sawdust  should  be 
removed  immediately  and  burned. 

"  Sulphur  Solution,"  made  by  dissolving  "  flowers  of 
sulphur  "  in  a  solution  of  sodium  carbonate,  should  be  kept 
on  hand  to  decompose  any  nitroglycerine  which  may  soak 
into  the  shelves  or  find  its  way  through  the  sawdust  to  the 
floor.  If  different  kinds  of  high  explosives  are  stored  in  the 
same  magazine,  they  should  be  placed  in  separate  sections  as 
far  as  possible.  No  acids  should  be  allowed  in  or  near  the 
magazine,  and  under  no  circumstances  whatever  should  fuses, 
blasting-caps,  or  detonators  be  stored  in  the  same  magazine  with 
high  explosives.  The  precautions  enumerated  for  the  care  of 
gunpowder  magazines  apply  with  equal  force  to  the  storage 
of  high  explosives. 

If  the  dynamite  be  in  the  form  of  cartridges,  the  boxes 
should  be  placed  so  that  the  cartridges  may  never  stand  in  a 
vertical  position.  If  not  perfectly  protected  from  moisture, 
dynamite  cartridges  undergo  a  material  change  in  appearance 
during  storage,  and  this  change  may  lead  those  who  are  not 
accustomed  to  handle  the  explosive  to  an  erroneous  conclu- 
sion as  to  its  condition.  The  change  is  due  to  the  absorption 
of  moisture  in  the  body  of  the  cartridge  which  dissolves  the 
alkaline  carbonate,  and  carries  the  latter  to  the  surface  of  the 
wrappers,  where  it  dries  and  forms  a  whitish  deposit.  This 
does  not,  however,  seriously  impair  the  condition  of  the 
explosive,  which  under  these  circumstances  should  be  ex- 
amined by  removing  some  of  the  explosive  from  the  wrapper 
and  testing  it  as  already  described,  since  no  clue  can  be 
obtained  from  the  litmus  paper. 

Guncotton  should  habitually  be  stored  in  a  thoroughly 
saturated  condition,  i.e.,  it  should  contain  from  30  to  35  per 
cent  of  water.  In  this  condition  it  is  practically  inexplosive. 
By  thoroughly  coating  the  boxes  with  a  composition  of 


MANIPULATION,  STORAGE,  AND    TRANSPORTATION.   385 

shellac  and  Stockholm  tar  dissolved  in  alcohol,  and  securing 
the  lids  snugly  by  screws,  they  may  be  made  practically 
water-tight. 

It  is  advisable  to  saturate  the  disks  of  guncotton  when 
they  are  received,  replace  them  in  the  boxes  with  strips  of 
blue  litmus  paper  on  top  and  between  one  or  two  disks,  and 
then  secure  the  tops.  The  boxes  should  then  be  weighed, 
and  their  weight,  together  with  the  data  on  the  boxes  of  other 
explosives,  noted  on  them.  At  the  monthly  inspections  of 
the  magazine  the  boxes  should  be  reweighed,  and  should 
there  be  any  appreciable  loss  of  weight  between  any  two 
consecutive  weighings,  the  disks  should  be  removed,  saturated 
with  water,  repacked,  and  fresh  litmus  paper  placed  in  the 
boxes. 

Dry  Guncotton  should  not  be  kept  in  the  magazine,  but 
when  required  for  primers  the  necessary  number  of  disks 
should  be  taken  out  and  dried.  Wet  disks  of  guncotton  may 
be  conveniently  dried  by  passing  a  clean  strong  string  through 
the  detonator-holes,  and  suspending  them  from  the  ceiling  of 
the  magazine.  A  disk  of  guncotton  of  the  usual  size  should 
weigh  approximately  10  ounces  when  dry. 

Although  it  is  not  usual  to  find  nitroglycerine  in  a  liquid 
state  at  military  posts,  the  following  suggestions  as  to  its 
storage  may  be  of  service. 

Nitroglycerine  is  usually  stored  in  quantities  of  45  or  50 
pounds  in  earthenware  crocks,  copper  cans,  or  tin  cans  which 
are  paraffined  on  the  inside,  and  provided  with  tubes  passing 
vertically  through  the  centre  of  the  cans.  When  stored  in 
crocks,  the  explosive  should  be  covered  with  a  layer  of  water, 
and  the  crocks  placed  in  copper  vessels  to  catch  the  nitro- 
glycerine in  case  of  breakage  from  any  cause.  The  cans  are 
closed  by  means  of  water-tight  tops. 

The  cans  or  crocks  should  always  be  placed  on  the  lowest 
tiers  or  shelves  in  the  magazine,  which  should  not  be  more 
than  eight  or  ten  inches  from  the  floor.  As  in  the  case  of 
other  high  explosives,  nitroglycerine  should  be  examined 


LECTURES   ON  EXPLOSIVES. 

monthly  by  testing  the  water  in  the  crocks  for  acidity,  or  by 
suspending  strips  of  litmus  paper  over  the  mouths  of  the  cans. 
Should  traces  of  acidity  be  discovered  and  there  are  means  at 
hand,  the  nitroglycerine  should  be  removed  from  the  magazine 
and  washed  as  already  described;  otherwise  it  should  be 
destroyed,  and  under  no  circumstances  should  an  attempt  be 
made  to  return  it  to  the  factory. 

Detonators  may  be  stored  in  small  buildings  of  similar 
construction  to  that  recommended  for  the  storage  of  high 
explosives,  but  such  a  building  should  not  be  located  within 
500  yards  of  any  other  magazine. 

Transportation  of  High  Explosives. — High  explosives 
when  properly  made  and  packed  are  quite  safe  against  any 
shock  to  be  expected  in  ordinary  transportation.  This  is  no 
longer  true,  however,  in  case  of  explosives  which  have  begun 
to  decompose  or  leak,  and  an  examination  should  always  be 
made  as  to  their  condition  before  transportation,  especially  if 
they  have  been  stored  for  any  length  of  time.  As  in  storage, 
so  in  transportation,  high  explosives  should  be  protected  from 
extremes  of  heat  and  cold.  On  steamships,  they  should  be 
stored  in  a  well-ventilated  place,  remote  from  the  engine- 
room,  preferably  on  deck,  unless  the  journey  is  to  be  a  pro- 
longed one  and  there  is  reason  to  expect  very  hot  or  cold 
weather.  In  the  former  case  they  should  be  protected  from 
the  direct  rays  of  the  sun,  and  in  the  latter  covered  with 
straw  and  tarpaulins. 

In  transportation  by  railway  it  is  well  to  cover  the  floors 
of  the  cars  with  straw;  this  precaution  should  be  observed  also 
in  transportation  by  wagons,  etc.  The  boxes  containing  the 
explosives  should  be  packed  so  that  there  is  no  danger  of 
falling,  and  in  the  case  of  cartridges  the  boxes  should  be 
placed  so  that  the  cartridges  will  lie  on  their  sides.  Whatever 
the  means  of  transportation,  they  should  be  protected  from 
water,  and  the  locality,  car,  or  wagon  should  be  plainly 
marked  Explosives — Dangerous. 

Under  no  circumstances  should  percussion  or  detonating 


MANIPULAT/ON,  STORAGE,  AND    TRANSPORTATION.   38? 

caps,  matches,  or  inflammable  material  of  any  kind  be  placed 
in  the  same  car,  wagon,  or  locality  with  high  explosives. 

The  above  precautions,  together  with  such  others  as  may 
be  suggested  in  any  particular  case,  will  greatly  reduce  the 
danger  incident  to  the  transport  of  high  explosives. 


LECTURE    XX. 

THE   APPLICATION   OF   HIGH    EXPLOSIVES   FOR   MILITARY 

PURPOSES. 

IT  does  not  fall  within  the  scope  of  these  lectures  to 
consider  the  extensive  operations  undertaken  by  military 
engineers  which  involve  elaborate  calculations  and  extend 
through  long  periods  of  time.  For  such  work,  large  amounts 
of  explosives  are  generally  used,  and  careful  preparation  is 
made  so  as  to  accomplish  only  the  object  in  view. 

In  the  case  of  hasty  demolitions,  such  as  ordinary  troops 
in  the  field  may  be  called  upon  to  execute,  economy  of  time 
and  absolute  certainty  of  success  are  the  principal  factors,  so 
that  nicety  of  calculation  and  extensive  preparation  are  pre- 
cluded, the  general  rule  being  to  be  sure  to  use  sufficient 
explosive  to  accomplish  the  object  in  view  (using  a  high  factor 
of  effectiveness)  and  to  place  it  so  as  to  produce  the  most 
destructive  effect. 

Conditions  to  be  Fulfilled  by  a  Military  Explosive. — 
For  military  purposes  an  explosive  should  satisfy  the  follow- 
ing conditions: 

1.  It  should  be  very  powerful. 

2.  It   should    be  stable   under    considerable   variation   of 
climate. 

3.  It  should  be  insensible  to  the  impact  of  projectiles. 

4.  It  should  be  plastic. 

5.  It  should  be  susceptible  of  easy  and  perfect  explosion 
or  detonation. 

388 


THE  APPLICATION  OF  HIGH  EXPLOSIVES.  389 

The  principal  objects  of  hasty  explosions  executed  by 
troops  are  felling  trees;  destruction  of  beams  of  wood,  iron, 
or  steel ;  demolition  of  bridges,  doors,  walls,  buildings,  etc. ; 
the  destruction  of  railway  tracks,  material  in  general,  and 
incidentally  the  removal  of  temporary  obstructions  in  water- 
ways, etc. 

Felling  Trees. — It  may  frequently  happen  that  trees  are 
to  be  felled  quickly,  either  to  clear  the  space  around  a  defen- 
sive work,  or  to  strengthen  a  position  by  means  of  an  abattis, 
or  for  various  other  reasons.  For  the  rapid  execution  of  such 
work,  time  and  labor  may  be  saved  by  the  use  of  high  explo- 
sives. To  fell  a  tree,  the  charge  may  be  located  in  one  of 
three  positions,  viz. : 

1 .  The  charge  may  be  placed  in  a  circle,  around  and  on  the 
outside  of  the  trunk. 

In  this  case  a  necklace  made  by  enclosing  the  cartridges, 
placed  end  to  end,  in  gunny-sacking,  canvas,  stiff  paper,  or 
other  material  at  hand,  is  attached  to  the  tree  at  the  distance 
above  the  ground  at  which  it  is  desired  to  cut  the  tree.  The 
primer  is  most  conveniently  placed  at  one  end  of  the  necklace. 
When  guncotton  disks  or  blocks  are  used,  the  necklace  may 
be  made  by  stringing  them  on  a  piece  of  stout  twine  or  wire. 

For  a  hardwood  tree  having  a  diameter  of  one  foot,  the 
charge  is  three  pounds  of  dynamite  No.  I,  or  other  explosive 
of  equal  force;  and  for  trees  of  other  dimensions  the  charge 
varies  as  the  square  of  the  diameter. 

2 .  The  charge  may  be  placed  on  one  side  of  the  tree. 

In  this  case  the  charge  may  be  placed  in  a  sack  and  hung 
against  the  tree,  or  it  may  be  placed  upon  a  beam  placed 
against  the  tree.  The  charge  is  calculated  as  in  the  preced- 
ing case,  but  should  be  one  fourth  greater  than  when  the 
necklace  is  used. 

3.  The  charge  may  be  placed  in  holes  bored  horizontally  in 
the  tree. 

The  hole  (or  holes)  is  bored  in  the  tree  with  a  wood  auger 
of  one  and  one-half  inch  in  diameter  to  a  distance  of  two 
thirds  of  the  diameter  of  the  tree  and  at  the  required  distance 


39°  LECTURES   ON  EXPLOSIVES. 

above  the  ground.  The  explosive  is  placed  in  the  hole  and 
tightly  compressed  with  a  wooden  rammer  so  that  it  com- 
pletely fills  the  cross-section;  the  primer  is  next  inserted,  and 
the  hole  tamped  with  wet  earth  or  clay. 

The  charge  for  trees  of  from  9  to  12  inches  diameter 
should  fill  the  hole  to  one  third  of  its  depth;  for  trees  having 
a  diameter  from  20  to  24  inches,  the  bore-hole  should  extend 
three  fourths  of  the  diameter,  and  the  charge  should  fill  the 
hole  to  one  half  of  its  depth;  for  trees  having  a  diameter 
greater  than  24  inches,  two  or  more  holes  should  be  bored 
and  charged  as  in  the  last  case. 

The  direction  of  the  fall  of  the  tree  may  be  determined  by 
securing  a  stout  rope  to  the  upper  portion,  and  taking  a  strain 
on  it  before  firing  the  charge. 

Destruction  of  Wooden  Beams.  —  Wooden  beams, 
squared*  such  as  are  used  in  bridge  timbers,  etc.,  may  be 
destroyed  in  any  of  the  three  ways  described  for  felling  trees. 

If  the  beam  is  square,  the  charge  is  calculated  by  the 
same  rules;  if  rectangular,  and  the  charge  is  to  be  placed 
uniformly  across  the  width  of  the  beam,  the  charge  may  be 
calculated  as  follows:  For  a  wooden  beam  12  inches  wide,  by 
6  inches  deep,  the  charge  of  dynamite  No.  I  is  10  ounces;  for 
beams  of  other  dimensions,  the  charge  varies  as  the  width  and 
the  square  of  the  depth.  Thus  to  break  a  beam  24  inches 
wide  by  9  inches  deep  would  require  a  charge  of  45  ounces. 

Destruction  of  Iron  and  Steel  Beams. — Wrought-iron 
beams  (or  plates)  having  a  uniform  width  of  one  foot  are 
destroyed  by  charges  calculated  as  follows,  and  placed  uni- 
formly across  the  beam:  A  beam  (or  plate)  twelve  (12)  inches 
wide  by  one-half  (i)  inch  thick  requires  a  charge  of  six  (6) 
ounces;  for  beams  (or  plates)  of  the  same  width,  but  of  vary- 
ing thickness,  the  charge  varies  as  the  square  of  the  thick- 
ness. For  beams  (or  plates)  of  varying  widths  as  well  as 
thicknesses,  whether  separate  or  built  up  in  the  form  of 
beams  or  girders,  the  charge  is  calculated  by  the  formula 

L  =  ctfb, 


THE  APPLICATION   OF  HIGH  EXPLOSIVES.  39 1 

in  which  L  =  the  charge  in  pounds; 

h  —  the  thickness  of  beam  (or  plate)  in  inches; 
b  —  the  width  of  beam  (or  plate)  in  inches; 
c  =  the  charging  coefficient. 
» 

For  dynamite  No.  i,  c  has  been  determined  experimen- 
tally as  follows: 

For  solid  wrought-iron  beams,/  =  o.  18; 
For  riveted  wrought-iron  beams,  c  =  0.09; 
For  solid  steel  beams,  c  —  0.25  ; 
For  riveted  steel  beams,  c  —  0.12. 

If  the  beam  or  plate  be  less  than  six  inches  in  width,  the 
charge  is  calculated  as  above,  and  placed  obliquely  across 
the  beam.  For  built-up  beams  or  girders  the  charges  are 
calculated  as  above,  and  are  placed  according  to  the  thick- 
ness of  the  different  places  in  the  cross-section,  taken  col- 
lectively. 

Demolition  of  Bridges. — The  charges  for  the  destruction 
of  the  several  parts  of  a  bridge,  whether  of  wood,  iron,  or 
steel,  are  calculated  as  just  described.  The  location  of  the 
charge  is  very  important,  and  depends  upon  several  considera- 
tions. The  most  complete  destruction  is  effected  by  placing 
the  charge  on  the  lower  flange  of  the  girder  at  the  centre  of 
the  span,  but  it  is  often  difficult  to  reach  this  point. 

Practically  the  best  place  for  the  charge  is  upon  the  lower 
girders,  near  an  abutment  or  pier,  and  at  a  point  where  the 
thickness  of  the  plates  is  least.  If  the  sections  are  uniform 
throughout  the  length  of  the  bridge,  or  if  it  ic  impracticable 
to  reach  the  lower  girder,  the  charge  should  be  placed  at  the 
centre  of  a  span  and  upon  the  upper  flange  of  the  upper 
girder. 

To  destroy  the  chains  of  a  suspension  bridge,  the  charges 
should  be  placed  in  the  alternate  spaces  between  the  plates  of 
which  the  chain  is  composed.  To  destroy  a  six-inch  wire- 
rope  or  cable  of  a  suspension  bridge  requires  about  twenty 


392  LECTURES   ON  EXPLOSIVES, 

pounds  of  dynamite  No.    I,  care  being  taken  to  attach  the 
charge  very  securely  and  closely  to  the  cable. 

Demolition  of  Doors. — To  destroy  a  doorway,  a  charge 
of  from  twenty  to  thirty  pounds  of  dynamite  No.  I  should  be 
enclosed  in  a  bag  or  piece  of  canvas,  and  suspended  from  a 
nail,  spike,  or  pickaxe  driven  in  the  middle  of  the  door.  To 
produce  the  same  effect  with  ordinary  black  powder,  the 
charge  should  be  from  two  to  three  times  greater,  and  placed 
at  the  bottom  of  the  door  and  covered  with  earth.  To  destroy 
palisades,  the  charge  is  placed  on  the  ground  at  the  foot  of 
the  pickets,  the  cartridges  end  to  end,  and  at  about  one 
pound  per  running  foot. 

Destruction  of  Railway-tracks. — To  destroy  a  rail  on  a 
first-class  railway  requires  from  10  to  12  ounces  of  dynamite 
No.  i,  or  guncotton,  two  ordinary  cartridges  of  the  former  or 
a  block  of  the  latter  forming  a  very  convenient  charge.  The 
charge  should  be  placed  in  close  contact  with  the  web  of  the 
rail,  and  if  practicable  secured  in  position,  which  can  generally 
be  done  by  taking  a  couple  of  half-hitches  around  the  rail 
with  the  fuse-wires.  The  charge  should  also  be  tamped  by 
covering  it  with  earth. 

For  rails  fixed  in  chairs,  the  charge  should  be  placed  in 
the  chair.  From  two  to  three  miles  of  track  per  hour  may 
be  effectually  destroyed  by  a  detail  of  eight  men. 

Destruction  of  Artillery  Material. — Field-guns  may  be 
destroyed  by  firing  a  charge  of  two  pounds  of  dynamite 
No.  i  attached  to  the  chase  near  the  muzzle  and  covered  with 
a  sod  of  earth.  To  destroy  a  siege-gun,  double  the  charge 
and  proceed  as  with  the  field-gun.  Either  gun  may  be 
destroyed  by  filling  the  bore  two-thirds  full  of  earth  or  sand, 
placing  the  above  charges  within  the  bore,  and  tamping  with 
moist  sand  or  earth  to  the  muzzle  and  firing.  In  the  latter 
case  there  is  danger  from  flying  pieces,  or  iron  or  steel. 

If  it  is  desired  to  break  the  piece  up  entirely  or  to  destroy 
a  gun  of  heavy  calibre,  it  may  be  accomplished  as  follows: 
Plug  the  vent  so  that  the  gun  is  water-tight,  and  bury  the 
piece  muzzle  upward,  so  that  the  muzzle  is  on  a  line  with  the 


THE   APPLICA  TION  OF  HIGH  EXPLOSIVES.  393 

surface  of  the  ground.  The  charge  is  calculated  from  the 
weight  of  the  gun,  at  the  rate  of  three  pounds  per  ton,  and  is 
divided  into  two  parts,  one  of  which  is  double  the  other. 
The  two  parts  of  the  charge  are  primed  separately  (but  con- 
nected in  the  same  circuit)  and  attached  to  a  wooden  rod,  so 
that  the  greater  will  be  at  the  base  of  the  bore  and  the 
smaller  slightly  above  the  trunnions  when  the  rod  is  intro- 
duced into  the  bore  of  the  gun.  The  rod  is  inserted  carefully 
into  the  bore,  which  is  next  filled  with  water  (or  earth),  the 
muzzle  closed  with  a  wooden  tompion,  and  the  charges  fired. 

Gun-carriages,  wheels,  etc.,  may  be  destroyed  according 
to  the  directions  already  given  for  the  destruction  of  wooden 
beams,  iron  plates,  etc. 

Removal  of  Temporary  Obstructions  in  Waterways. 
— In  addition  to  the  hasty  demolitions  undertaken  by  troops, 
already  enumerated,  it  sometimes  becomes  necessary  to 
remove  temporary  or  even  permanent  obstructions  in  water- 
ways. To  blast  or  cut  off  piles  driven  in  a  channelway  or 
elsewhere  in  water,  a  convenient  method  is  to  attach  the 
charge  to  a  hoop  and  lower  it  into  position  by  means  of  stout 
twine  and  weights,  or  by  a  pole,  slipping  the  hoop  over  the 
pile.  If  a  row  of  piles  is  to  be  attacked,  the  charge  is  con- 
veniently attached  to  a  horizontal  pole  instead  of  a  hoop,  and 
placed  in  position  in  the  same  way.  The  charge  may  be  put 
in  rubber  or  other  water-proof  bags,  but  it  should  be  put 
preferably  in  tin  canisters.  The  precautions  as  to  the  proper 
method  of  insulation,  etc.,  have  already  been  alluded  to  in  a 
previous  lecture.  To  completely  cut  off  a  pile  from  twelve 
to  fourteen  inches  in  diameter  under  water,  requires  a  charge 
of  one  pound  of  dynamite  No.  I. 

Piles  or  stumps  partially  embedded  in  a  river-bottom  may 
be  removed  by  attaching  the  necessary  charge  to  the  end  of 
a  long  pole,  and  gradually  and  carefully  placing  the  charge 
under  or  partially  under  the  object  to  be  loosened. 

Sunken  vessels  are  more  difficult  to  remove,  and  require 
much  larger  charges  of  explosive.  Masts  may  be  cut  away 


394  LECTURES   ON  EXPLOSIVES. 

at  the  deck  as  already  described  for  piles.  To  destroy  hullsr 
the  charges  should  be  placed  in  the  interior  of  the  wreck,  if 
possible,  and  the  services  of  a  diver  may  be  necessary. 
Should  the  water  be  not  too  deep,  and  the  hatches  be  open, 
however,  charges  of  twenty-five  or  thirty  pounds  of  dynamite 
lowered  into  the  hatches,  fore  and  aft,  will  generally  suffice 
to  open  up  the  hull  completely,  and  the  remaining  wreckage 
may  be  destroyed  as  indicated. 

In  swift  currents,  the  charges  may  be  placed  in  iron  pipes 
and  lowered  alongside  of  the  wreck  and  fired,  the  pipes  acting 
as  anchors  to  hold  the  charges  in  position.  When  two  or 
more  charges  are  to  be  fired  simultaneously  under  water,  they 
should  be  placed  singly,  and  the  wires  leading  to  each  charge 
brought  to  surface  and  connected  in  the  circuit  very  carefully. 
In  all  submarine  blasting,  it  will  prove  economical,  both  as 
to  time  and  expense,  to  use  large  charges  so  as  to  insure  the 
full  effect  desired. 

To  remove  ice  so  as  to  open  navigation,  dynamite  may  be 
advantageously  used.  In  running  water  the  operation  should 
be  begun  in  places  where  the  loosened  ice  can  be  carried  away 
by  the  current.  By  placing  charges  near  the  shore  and  cover- 
ing them  with  earth,  and  proceeding  from  shore  to  shore  with 
charges  under  the  ice,  the  maximum  effect  is  obtained. 
Vessels  which  have  been  blocked  up  in  ice  may  be  freed  in  a 
similar  manner. 

Relative  Force  of  Explosives. — The  formulae  by  which 
the  charges  have  been  calculated  in  the  preceding  pages  for 
the  accomplishment  of  various  kinds  of  work  are  purely 
empirical,  and  are  true  only  for  dynamite  No.  I  and  gun- 
cotton.  When  other  explosives  are  used,  these  formulae  must 
be  modified  according  to  the  relative  strength  of  the  explo- 
sive used.  For  that  purpose  the  following  table,  which  was 
established  by  means  of  the  Quinan  pressure-gauge,  may  be 
used: 


THE  APPLICATION  OF  HIGH  EXPLOSIVES. 


395 


Name  of  Explosive. 

Compression 
of 
Cylinder. 

Order 
of 
Strength. 

o"  ">8^ 

106  17 

(Made    irom    nitroglycerine    after    the 
Vonges  process.) 
II     Hellhoffite                                            

cge 

ce  T 

(Made  Nov.  19,  1889,  tested  Jan.  6,  1890.) 
j'y    Nobel's  smokeless  powder  

cod 

02  ^8 

V    Nitroglycerine  

COQ 

Q2  "\1 

(Made  Jan.  29,   1890,  and  tested  on  the 
same  day.      U.  S.  N.  Torpedo-station  proc- 
ess.) 

4QO 

88  QI 

(Made  from  the  last  nitroglycerine.) 

.4^8 

8q   12 

(U.  S.  N.  Torpedo  Station,  Lot  100,  1889.) 

.4^8 

8^  12 

(Stowmarket,  1885.) 

A  e  T 

81  85 

(Made  according  to  the  French  process 
and  tested  on  the  same  day  )  

44.8 

81  31 

(Made  in  Artillery  School  Laboratory.) 
XI     Dynamite  No    i  

44.8 

81  31 

.4^7 

7Q  ^1 

42Q 

77  86 

.185 

60  87 

XV    Oxonite    

.18-3      ' 

60.^1 

(Picric  acid  fused  before  being  added.) 
XVI    Tonite    

.376 

68.24 

XVII     Bellite                 •                           

^62 

QC     7Q 

XVIII     Oxonite  

.-354 

64.24 

(Picric  acid  not  fused.) 
XIX    Rackarock                  

•240 

6l  71 

.•3-50 

60.4.^ 

.7-2.2 

60,25 

XXII     Volney's  powder  No    I  

.^22 

c8.44 

.2Q4 

c-i.iS 

XXIV     Melinite    ...                  

.280 

«;o.82 

XXV    Silver  fulminate     

.277 

50.27 

.275 

49.91 

XXVII     Mortar  powder  

.155 

28.13 

(Dupont.) 

Champion's  Experiments  with  High  Explosives  during- 
the  Franco-Prussian  War. — M.  Champion,  of  the  French 
Artillery  Corps,  furnishes  the  following  valuable  information, 
which  he  gathered  during  a  series  of  practical  trials  in  the 
siege  of  Paris  by  the  Prussians. 


39^  LECTURES   ON  EXPLOSIVES. 

Destruction  of  Palisades. — The  palisade,  which  was  con- 
structed in  view  of  the  experiment,  had  a  length  of  one  metre, 
and  was  of  the  ordinary  model. 

At  the  base  a  cartridge  containing  five  pounds  of  50$  dyna- 
mite was  placed.  The  explosion  destroyed  all  the  stakes, 
and  the  fragments  were  projected  in  all  directions. 

Complete  rupture  of  palisades  of  the  ordinary  model  was 
produced  by  exploding  cartridges  charged  with  four  pounds 
of  dynamite,  and  suspended  at  their  ends  from  the  palisades. 
The  same  effect  was  also  produced  by  zinc  tubes  containing 
five  and  a  half  pounds  of  dynamite  per  running  metre,  placed 
at  the  foot  of  the  palisades. 

In  the  first  explosion,  out  of  fourteen  stakes,  nine  were 
cut  at  the  height  of  the  cartridge;  five  were  injured  more  or 
less  without  being  thrown  down.  In  the  second  explosion, 
five  stakes  which  were  in  front  of  the  cartridge  were  cut  away. 

The  fact  was  also  established  in  the  second  explosion,  that 
no  splinters  were  thrown  in  the  direction  of  the  operator. 

Doors  and  Wooden  Enclosures. — Small  cartridges,  weighing 
three  to  four  ounces,  were  hung  up  on  nails  along  the  walls, 
about  four  inches  apart.  By  exploding  one  of  them,  the 
other  cartridges  exploded  simultaneously  along  the  whole  line. 

The  weight  of  the  cartridges  varied  with  the  thickness  of 
the  obstacles. 

Tamping,  in  both  cases,  would  diminish  the  quantity  of 
explosive  used,  without  modifying  the  result.  Sacks  of  earth, 
or  any  debris  can  be  employed  for  tamping. 

Trials  on  Walls. — The  third  series  of  experiments  was 
made  on  a  wall  two  feet  high  and  one  and  a  half  feet  wide, 
constructed  of  rough-stone  masonry,  joined  by  good  mortar, 
and  forming  regular  layers  in  the  lower  part. 

The  wall,  covered  with  a  coping  of  flagstone,  was  very 
solid,  and  made  of  the  very  best  kind  of  material,  and  could 
be  considered  as  a  very  substantial  structure. 

A  can  containing  three  kilograms  eight  hundred  grams  of 
50$  dynamite  was  placed  vertically  at  the  foot  of  the  wall, 
and  the  cap  was  introduced  through  the  cork  stopper,  and 


7 'HE  APPLICA  TION   OF  HIGH  EXPLOSIVES. 

the  charge  fired.  A  gap  of  eighty  centimetres  wide  and 
eighty-five  centimetres  high  was  opened  at  the  foot  of  the 
wall.  The  same  aspect  of  the  opening  was  noticeable  on 
both  facings  of  the  wall. 

The  rocks  flew  in  both  directions,  so  that  with  a  small 
hammer  it  was  enlarged  to  an  opening  of  one  metre  fifteen 
centimetres  high,  and  one  metre  seventy  centimetres  wide. 

A  second  trial  was  made  under  the  same  conditions,  but 
covering  the  can  of  explosive  by  four  sacks  filled  with  sand. 
The  effect  was  notably  increased ;  and  the  breach  made  was 
one  metre  seventy  centimetres  wide  by  two  metres  forty 
centimetres  high,  and  the  base  of  it  was  covered  with  rocks 
to  a  height  of  seventy  centimetres.  The  wall  was  shaken  to 
the  top,  and  two  metres  fifty  centimetres  in  width. 

The  sacks  of  sand  were  projected  to  a  distance  of  twenty- 
five  metres  back  of  the  explosive,  and  some  bowlders  were 
sent  flying  to  a  distance  of  sixty  metres  in  front  of  it. 

Therefore  the  tamping  augmented  very  largely  the  effects 
of  dynamite;  but  the  weight  of  the  sacks  renders  them  incon- 
venient '  o  carry,  especially  when  in  the  presence  of  an  enemy 
and  when  the  work  has  to  be  rapidly  executed. 

In  the  third  trial  the  object  in  view  was  to  determine  the 
most  advantageous  method  for  placing  the  dynamite  can 
against  the  wall,  without  being  obliged  to  cover  it  with  sand. 
It  was  placed  against  the  wall,  on  a  slab  about  seventy  centi- 
metres high,  and  was  fired  without  any  other  preparation. 

The  breach  about  fifty  centimetres  above  the  ground 
presented  an  opening  of  eighty  centimetres  in  width  and  one 
metre  in  height  on  the  face  against  which  the  explosive  was 
placed,  and  one  metre  by  one  metre  fifty  centimetres  on  the 
opposite  side. 

The  wall  was  also  shaken  two  metres  high  and  two  metres 
wide,  and  the  breach  could  be  enlarged  by  hand.  There  is, 
according  to  this  trial,  a  great  advantage  in  raising  the  charge 
of  dynamite  about  one  third  of  the  height  of  the  wall,  instead 
of  placing  it  on  the  ground. 


LECTURES   ON  EXPLOSIVES. 

A  fourth  experiment  was  made  to  substantiate  an  experi- 
ment previously  made  by  M.  Champion. 

He  had  established  the  fact  that  when  a  charge  of  dyna- 
mite is  placed  against  one  of  the  walls  in  the  interior  of  a 
room  only  one  breach  in  this  wall  is  made,  whereas  the  three 
others  are  thrown  down;  on  the  contrary,  if  the  charge  is 
placed  in  the  middle  of  the  room,  the  four  walls  would  tumble 
down.  The  question  naturally  arose,  if  it  would  not  be 
advantageous  to  place  the  charges  at  some  distance  from  the 
wall  which  it  was  desired  to  destroy. 

Four  kilograms  of  dynamite,  in  two  canvas  sacks,  were 
placed  on  a  little  earth-knoll  about  fifteen  centimetres  high 
and  fifty  centimetres  from  the  wall,  and  surrounded  by  small 
sacks  full  of  earth,  but  open  against  the  face  of  the  wall.  The 
explosion  produced  only  a  small  breach,  fifty  centimetres  by 
fifty  centimetres;  but  the  wall  was  shaken  up  to  its  full  height 
and  three  metres  in  width.  The  slabs  on  the  coping  of  the 
wall  were  displaced.  With  very  little  exertion,  and  without 
tools,  all  the  shaken  part  could  be  taken  down. 

Probably  enclosure  walls,  which  are  generally  of  poor 
masonry,  can  be  best  destroyed  in  this  manner. 

The  quantity  of  the  dynamite  charge  should  be  in  propor- 
tion to  the  solidity  of  the  wall. 

The  less  solidity  a  wall  possesses,  the  more  difficult  it  will 
be  to  throw  it  down,  or  to  make  a  breach  in  it ;  as  a  bad  wall 
gives  way  easily  to  the  breaking  effect  of  the  explosion,  and 
propagates  the  shock  but  little.  The  charge  is  therefore 
placed  at  a  greater  distance,  and  has  a  chance  to  act  on  a 
greater  surface;  and,  owing  to  the  bad  construction  of  the 
wall,  it  will  throw  it  down. 

A  fifth  experiment  was  made. 

In  a  box  twenty-four  centimetres  by  fourteen  centimetres, 
four  cartridges  of  dynamite  were  placed,  each  cartridge  weigh- 
ing seventy-five  grams;  and  they  were  placed  at  one  metre 
thirty  centimetres  above  the  ground.  The  explosion  opened 
a  breach  sixty  centimetres  by  thirty  centimetres  opposite  the 


THE  APPLICA  TION  OF  HIGH  EXPLOSIVES.  399 

charge,  and  seventy  centimetres  by  ninety  centimetres  on  the 
other  side  of  the  wall. 

The  shock  also  fissured  the  wall,  so  as  to  enlarge  the 
opening  to  one  centimetre  by  eighty  centimetres,  one  metre 
above  the  ground.  In  fact,  all  the  experiments  were  conclu- 
sive in  favor  of  the  employment  of  dynamite  in  preference  to 
gunpowder,  when  it  is  desired  to  produce  quick  effects. 

Its  weight  is  very  small  as  compared  to  that  of  powder 
required  to  produce  the  same  effect,  and  the  charge  need  not 
be  tamped  to  give  satisfactory  results.  Consequently,  without 
fatigue,  a  sapper  can  carry  to  great  distances  all  that  is 
required  to  make  a  breach  in  a  wall  for  giving  passage  to  a 
whole  regiment  if  necessary. 

Destruction  of  Walls  at  Buzenval. — The  enemy  was  in- 
trenched behind  the  enclosure  of  the  park.  A  first  explosion 
produced  a  breach.  The  operation  presented  great  difficul- 
ties. The  men  who  had  to  carry  the  explosives  were  few  in 
number.  Nevertheless,  some  soldiers  and  men  of  the  en- 
gineering corps  volunteered  under  the  directions  of  M.  Pellet, 
and  approached  the  indicated  spots,  and,  by  means  of  canvas 
sacks  containing  two  kilograms  of  dynamite,  made  openings 
which  permitted  some  soldiers  to  pass  through.  The  walls 
were  thin,  and  it  was  only  necessary  to  fire  the  charges  with- 
out tamping  to  open  these  breaches. 

Destruction  of  Houses. — First.  In  a  small  dwelling  at 
Drancy,  about  twelve  feet  wide,  four  kilograms  of  dynamite 
were  placed  inside  the  building  and  against  the  wall.  Doors 
and  windows  were  left  open.  The  house  was  thrown  down 
without  projection  of  building  material,  and  only  the  wall 
against  which  the  dynamite  was  placed  remained  standing, 
although  the  walls  were  cracked  and  fissured. 

Second.  Stone  cabin  at  Bobigny.  Thickness  of  wall, 
thirty  centimetres.  Four  kilograms  50$  dynamite,  the  same 
as  in  the  preceding  example,  were  placed  in  a  corner 
which  seemed  to  offer  the  most  resistance,  opposite  the 
door. 


4OO  LECTURES   ON  EXPLOSIVES. 

The  cabin  was  completely  destroyed,  and  the  rocks  went 
flying  in  all  directions. 

It  is  preferable,  in  destroying  buildings,  to  place  the 
charge  in  the  middle  of  the  room,  as  an  even  pressure  is 
exerted  on  the  surface  of  the  exploding  chamber;  experience 
has  confirmed  this  theory. 


LECTURE    XXI. 

THE   USE   OF   HIGH    EXPLOSIVES   IN    SHELL. 

AMONG  the  many  practical  uses  to  which  high  explosives 
may  be  applied  for  military  purposes  is  that  of  bursting- 
charges  in  shell. 

It  hardly  comes  within  the  province  of  these  lectures  to 
consider  the  many  special  machines  which  have  been  devised 
to  throw  large  masses  of  various  high  explosives  contained 
in  specially  constructed  projectiles,  but  a  brief  resume  of  the 
attempts  that  have  been  made  to  fire  either  the  ordinary  or 
special  shells  from  powder-guns  may  prove  of  material  assist* 
ance  to  us. 

Experiments  with  Shell  charged  with  Guncotton. — 
Attempts  to  use  guncotton  as  a  bursting-charge  for  shell  were 
made  as  early  as  1864,  when,  under  the  direction  of  the 
English  Guncotton  Committee,  twenty-five  rounds  were  fired 
with  unfused  shell  charged  with  dry,  long-staple  guncotton. 

The  first  ten  rounds  were  successfully  fired  from  a  lO-inch 
smooth-bore;  the  next  ten  rounds  were  fired  from  a  13-inch 
mortar  with  like  success.  But  of  the  last  five  rounds,  which 
were  fired  from  a  /-inch  B.  L.  Armstrong,  two  of  the  shells 
burst,  one  just  beyond  the  muzzle,  and  the  other  (last)  within 
the  bore,  and  injured  the  gun  to  such  an  extent  as  to  render 
it  unfit  for  further  service. 

It  was  believed  that  these  explosions  were  due  to  the 
compression  or  friction  produced  by  the  "  setting  up  "  of  the 
comparatively  loose  charges  at  the  moment  of  starting. 

In  1867  experiments  were  resumed  with  compressed 

401 


4O2  LECTURES   ON  EXPLOSIVES. 

pulped  guncotton.  Two  steel  shell  compactly  filled  with 
disks  of  guncotton  were  fired  from  an  8-inch  shunt-gun,  the 
first  bursting  after  one  graze  on  the  range,  the  second  burst- 
ing in  the  bore,  shattering  the  chase,  and  leaving  nothing  in 
front  of  the  trunnions. 

During  the  same  series  of  experiments  one  round  was 
fired  from  a  7-inch  M.  L.  Woolwich  gun.  The  shell  burst  in 
the  bore,  cracking  and  expanding  the  gun,  which,  however, 
remained  entire.  In  these  experiments  ordinary  shell  were 
used,  the  only  precaution  observed  being  the  wrapping  and 
packing  of  the  explosive. 

In  1882  similar  experiments  were  instituted  in  Germany 
to  determine  the  possibility  of  using  large  charges  of  gun- 
cotton  in  projectiles  for  the  21 -centimetre  mortar.  The  shell 
were  of  cast  steel  with  very  thin  walls  and  five  calibres  in 
length.  Apparently  these  experiments  were  successful,  since 
at  present  guncotton  shell  which  are  made  in  two  parts  are 
used  in  this  mortar.  These  shell  consist  of  a  head  and  body 
which  are  secured  together.  The  charge,  which  is  enclosed 
in  a  zinc  or  iron  box,  consists  of  compressed  guncotton  disks 
5  cm.  thick  and  containing  20  per  cent  of  water.  The  upper 
disk  is  provided  with  a  cylindrical  cavity  to  receive  a  primer 
of  dry  guncotton,  which  in  turn  is  perforated  to  receive  the 
detonator.  When  the  charge  is  placed  in  the  box  a  wooden 
rod  is  inserted  in  the  detonator-hole,  and  melted  paraffin  is 
poured  in  to  fill  the  insertion  of  the  detonator.  To  load  the 
shell  the  charge  is  introduced  into  the  box  as  indicated,  and 
the  box  placed  in  the  shell  and  the  head  of  the  latter  screwed 
on.  A  hollow  screw  is  inserted  in  the  eye  of  the  shell  to  hold 
the  box  in  place,  and  finally,  immediately  before  being  placed 
in  the  gun  or  mortar,  the  fuse  and  detonator  are  inserted  in 
the  aperture  in  the  screw. 

These  projectiles  have  given  good  satisfaction,  not  only  in 
the  2i-cm.  mortar,  but  also  in  the  15-  and  28-cm.  pieces. 

This  projectile  is  similar  in  nearly  every  particular  to  the 
one  recently  invented  by  Von  Forster  and  Wolff,  in  which 
granulated  guncotton  is  used. 


THE    USE   OF  HIGH  EXPLOSIVES   IN  SHELL.  403 

The  further  record  of  experiments  conducted  by  the 
German  Government  refers  more  to  the  action  of  the  fuses 
used  with  shell  charged  with  guncotton  than  to  investigating 
the  possibility  of  extending  the  use  of  such  bursting-charges 
to  guns  of  larger  calibre  and  rifled  pieces. 

In  this  country,  however,  the  importance  of  this  latter 
line  of  investigation  was  recognized,  and  in  1884  Commander 
Folger,  U.  S.  Navy,  succeeded  in  firing  fifteen  rounds  of 
guncotton  at  a  range  of  200  yards  with  the  8o-pounder  B.  L. 
rifle,  using  full  charges  of  powder.  The  shell  were  filled  with 
guncotton  saturated  with  water,  and  no  precaution  was  taken 
to  relieve  the  shock  upon  the  first  impulse  beyond  placing  a 
layer  of  oakum  one  quarter  of  an  inch  thick  in  the  base  of  the 
shell.  In  loading  these  shell  the  ordinary  service  disks  were 
broken  up  in  order  to  introduce  the  explosive  through  the 
fuse-hole;  the  density  was  consequently  greatly  reduced. 

These  experiments  were  followed  by  others,  conducted  at 
the  U.  S.  Naval  Torpedo  Station,  to  test  thoroughly  the 
safety  of  the  service  guncotton  as  bursting  charges  for  fused 
shell  fired  from  service  guns  under  service  conditions.  Un- 
fortunately the  only  guns  available  for  these  experiments  were 
Dahlgren  24-pounders  and  2O-pounder  M.  L.  rifles. 

Special  shell  were  made  for  the  tests.  For  trial  with  the 
24-pounders  they  were  of  cast  iron,  fitted  with  base-plugs  and 
ogival  heads,  and  had  an  exterior  diameter  of  5f  inches, 
interior  diameter  of  5  inches,  and  length  of  8  inches.  The 
space  between  the  disks  and  the  walls  of  the  shell  was  well 
filled  with  fine  sawdust  and  rammed.  Full  service  charges 
of  powder  were  used  in  the  tests. 

In  the  first  four  rounds  from  this  gun  the  shell  charge 
consisted  of  three  and  one-half  disks  of  wet  guncotton, 
weighing  4^  pounds  each,  the  loaded  shell  weighing  30  to  32 
pounds. 

The  first  shot  was  fired  pointblank  at  the  masonry  escarp- 
ment of  the  fort  on  Rose  Island,  50  yards  distant  from  the 
muzzle.  The  shell  was  broken  up  and  the  guncotton  scattered, 
but  no  explosion  followed. 


404  LECTURES   ON  EXPLOSIVES. 

The  second  shot,  fired  under  similar  conditions,  struck  in 
the  crevices  of  the  masonry  and  buried  itself  in  the  earth 
behind  the  wall.  It  was  recovered  intact,  except  that  a  frag- 
ment was  broken  from  the  projecting  base-plug,  and  was  fired 
again  (fourth  shot)  at  the  butt,  the  result  being  similar  to  that 
of  the  first  shot. 

The  third  shot  was  fired  up  the  bay,  and,  although  it 
ricochetted  along  the  water,  it  neither  exploded  nor  broke  up. 

The  fifth  shell  was  loaded  with  one  dry  and  three  wet 
disks;  the  sixth  with  two  dry  and  two  wet;  and  the  remain- 
ing four  were  charged  with  four  dry  disks  each. 

These  last  shots  were  all  fired  into  the  escarpment,  and, 
although  the  shell  broke  up  on  impact,  there  was  no  explo- 
sion, either  in  the  gun,  during  flight,  nor  upon  impact. 

The  shell  used  with  the  2O-pounder  were  made  of  four- 
inch  steel  tubing,  one  quarter  of  an  inch  thick,  fitted  with 
conical  heads  and  movable  base-plugs,  and  were  of  such 
diameter  that  the  disks  fitted  them  snugly  without  packing. 
The  only  precaution  against  the  initial  shock  was  the  placing 
of  an  asbestos  gasket  over  the  base-plug.  The  full  service 
charge  of  powder  was  used,  and  all  other  service  conditions 
observed. 

The  first  four  shell  were  loaded  with  from  4  pounds 
9  ounces  to  6  pounds  6  ounces  of  wet  service  guncotton,  and 
fired  into  the  butt,  with  the  result  that  there  was  no  explosion  ; 
the  shell,  however,  being  distorted  and  crushed,  but  still  con- 
taining some  of  the  explosive,  the  rest  being  scattered  around. 

In  the  five  following  shots  the  shell  were  loaded  with  thin 
(J-inch)  disks  made  by  splitting  the  ordinary  disks,  and  the 
guncotton  was  dry.  The  result  of  the  fifth  shot  was  identical 
with  those  preceding,  but  the  last  five  shell  broke  up  in  the 
gun  without  explosion  of  the  guncotton  or  damage  to  the 
piece. 

These  experiments  were  continued  at  the  U.  S.  Naval 
Ordnance  Proving  Grounds,  where  six  shots  were  fired  from  a 
6-inch  B.  L.  rifle.  The  projectiles  were  elongated  shrapnel 
cases  with  movable  heads.  As  in  the  experiments  already 


THE    USE   OF  HIGH  EXPLOSIVES  IN  SHELL.  405 

recorded,  it  was  proven  beyond  a  doubt  that  it  was  possible 
to  fire  shell  loaded  with  guncotton,  wet  or  dry,  from  the 
ordinary  powder-guns,  using  service  charges  and  under  service 
conditions. 

Experiments  with  Shell  charged  with  Nitroglycerine.— 
During  the  year  1885  a  curious  and  novel  device  of  Mr. 
C.  P.  Winslow  was  tested  by  the  Naval  Ordnance  Board. 
The  device  was  a  high  explosive  shell,  so  arranged  that  the 
bursting-charge — nitroglycerine — was  to  be  made  during  the 
flight  of  the  projectile,  and  fired  upon  impact,  either  by  shock 
or  by  means  of  a  specially  prepared  fuse. 

The  shell  consisted  of  two  glass  jars,  one  within  the  other, 
the  inner  one  containing  a  mixture  of  nitric  and  sulphuric 
acids  in  the  proportions  by  volume  of  4  :  3,  and  the  outer 
one  glycerine  and  sulphuric  acid  in  the  proportions  of  6  :  I ; 
the  two  jars  containing  equal  volumes  of  the  mixtures.  These 
jars  were  fastened  together  by  means  of  screw-caps  and  intro- 
duced into  a  tin  cylinder,  which  in  turn  was  placed  within 
the  shell  proper.  The  shell  itself  consisted  of  two  sections, 
which  were  securely  joined  after  the  cylinder  containing  the 
jars  had  been  inserted.  Rupture  of  the  jars  at  the  time  of 
firing  was  prevented  by  transverse  bars  in  the  shell,  to  which 
the  exterior  jar  was  securely  fastened  by  means  of  rubber 
bands. 

To  cause  the  shell  to  explode  at  any  point  of  its  flight,  a 
time-fuse  properly  cut  ignited  a  priming  of  rifle-powder,  and 
forced  a  plunger  contained  in  the  rear  section  of  the  shell 
violently  forward,  thus  breaking  the  jars.  The  rotation  of  the 
shell  and  broken  glass  were  then  supposed  to  mix  intimately 
the  contents  of  the  jars,  thus  forming  nitroglycerine,  which 
was  exploded  by  shock  upon  impact,  or,  if  that  failed,  by 
means  of  a  secondary  charge  of  rifle-powder  contained  in  an 
axial  chamber  of  the  plunger. 

Experiments  with  this  device  proved  very  unsatisfactory, 
and  the  shell  was  condemned.  In  1887  the  SmolianinofT 
method  of  firing  nitroglycerine  from  powder-guns  was  tested 
at  the  Naval  Torpedo  Station.  The  nitroglycerine  was  first 


LECTURES   ON  EXPLOSIVES. 

rendered  insensitive  by  treating  it  with  liquid,  the  character 
of  which  was  kept  secret,  and  then  completely  filling  the  shell 
with  the  explosive,  and  inserting  a  burster  to  which  was 
attached  a  time-fuse.  The  24-pounder  howitzer  was  used, 
and  twenty  rounds  were  fired  with  the  service  charge  of 
powder.  The  shell  held  from  one  to  one  and  one-half  pounds 
of  the  liquid,  which  contained  97  per  cent  of  nitroglycerine. 

Five  shell  were  unf used  and  fired  into  a  masonry  wall,  fifty 
yards  distant  from  the  gun,  with  the  result  that  all  were  broken 
up,  but  apparently  without  explosion.  The  remainder  were 
fired  up  the  bay,  and,  with  the  exception  of  three,  they 
exploded  in  midair  at  the  time  fixed,  with  a  sharp  report, 
scattering  the  fragments  of  the  shell  over  a  very  wide  area. 

Previous  to  these  experiments  the  inventor  claimed  to 
have  fired,  without  accident  or  premature  explosion  of  any 
kind,  over  300  shell  from  a  condemned  2O-pounder  Parrott 
rifle. 

During  the  same  year  these  experiments  were  repeated 
before  the  Army  Ordnance  Board  at  Sandy  Hook  with  equal 
success.  In  these  latter  trials  the  shell,  weighing  from  82  to 
89  pounds,  and  containing  from  4.1  to  4.6  pounds  of  the  pre- 
pared nitroglycerine,  were  fired  from  a  loo-pounder  Parrott 
rifle.  At  the  conclusion  of  the  Newport  trials,  the  Navy 
Board  reported  that  the  Smolianinoff  method  of  firing  nitro- 
glycerine from  ordinary  powder-guns  was  feasible,  and  recom- 
mended that  further  experiments  be  made  to  test  its  value  for 
guns  of  greater  calibre. 

Experiments  with  Shell  charged  with  Dynamite. — In 
1867  shell  charged  with  dynamite  were  successfully  fired  in 
Sweden  from  an  i8-pounder  howitzer  with  about  two  pounds 
of  gunpowder.  Three  years  later,  during  the  winter  of 
1870-71,  similar  experiments  were  undertaken  in  Germany 
with  a  6.8-inch  Krupp  gun.  Shell  fully  charged  with  dyna- 
mite were  fired  without  accident,  using  very  small  powder- 
charges,  but  when  the  latter  was  increased  to  1.65  pounds 
the  shell  burst  in  the  bore. 

Two  shells  were  successfully  fired  during  the  siege  opera- 


THE    USE   OF  HIGH  EXPLOSIVES  IN  SHELL,  407 

tions  of  the  Second  Corps  of  the  Army  of  Versailles  (1871),  one 
from  a  24-pounder  howitzer,  the  other  from  a  mortar.  The 
dynamite  was  enclosed  in  a  rubber  bag  held  in  position  with 
gunpowder,  and  was  ignited  by  time-fuses. 

In  1874  Commander  Barker,  U.  S.  Navy,  fired  without 
accident  of  any  kind  at  the  Torpedo  Station,  nine  shell 
charged  with  dynamite  from  a  24-pounder  howitzer.  Full 
service  charges  of  gunpowder  were  used,  and  all  service  con- 
ditions as  to  the  shell  were  observed.  Three  of  the  shell  were 
unfused  and  were  fired  into  the  wall  of  an  old  bomb-proof, 
exploding  upon  impact.  The  remaining  six  were  fused  (Bor- 
mann)  and  fired  up  the  bay,  none  exploding  prematurely,  and 
some  of  them  at  the  fixed  time.  In  1884  experiments  were 
made  with  firing  dynamite  from  powder-guns,  using  a  special 
form  of  shell  designed  by  Mr.  F.  H.  Snyder. 

The  shell  consisted  practically  of  a  sabot,  built  up  of 
gelatinized  fibre,  leather,  and  copper  disks  placed  next  to  the 
powder-charge;  next  came  a  brass  case  containing  a  cellular 
rubber  buffer,  and  then  a  wooden  plunger  for  compressing 
the  buffer,  and  finally  the  magazine  for  holding  the  dyna- 
mite. 

These  shell  proved  unsuccessful  at  the  time,  although  the 
inventor  claims  to  have  overcome  the  difficulties  and  to  have 
successfully  fired  shell  charged  with  five  pounds  of  dynamite. 
During  the  same  year  Commander  Folger,  U.  S.  Navy,  fired 
22  shell,  each  containing  5J-  ounces  of  dynamite  from  a 
12-pounder  (10  rounds  being  fired  under  service  conditions), 
the  only  precaution  taken  in  loading  the  shell  being  a  little 
oakum  introduced  as  a  packing. 

In  1886  a  shell  designed  by  Mr.  J.  W.  Graydon  (at  that 
time  Lieutenant,  U.  S.  Navy)  was  tested  at  the  Presidio, 
San  Francisco;  52  unfused  shell  containing  dynamite  No.  I 
being  fired  from  a  4^-- inch  siege-gun,  using  the  service-powder 
charge.  These  experiments  were  conducted  before  a  Board 
of  U.  S.  Army  Officers  appointed  to  investigate  and  report 
upon  the  invention,  and  were  so  successful  that  the  board 
unanimously  recommended  that  the  trials  be  continued  with 


408  LECTURES   ON  EXPLOSIVES. 

the  8-inch  converted  M.  L.  rifle  and  the  1 5-inch  smooth-bore 
gun. 

The  shell  was  loaded  and  prepared  for  firing  as  follows: 
.It  was  first  lined  with  asbestos  paper,  two  thicknesses  being 
placed  on  the  bottom,  and  the  dynamite  was  then  introduced 
in  paraffined  packages  and  rammed  with  wooden  rammers 
until  the  shell  was  filled.  Between  the  base  of  the  projectile 
and  the  powder-charge  were  inserted  eight  asbestos  wads. 
Experiments  with  this  system  were  continued  the  following 
year  by  the  Army  Ordnance  Board  at  Sandy  Hook. 

A  7-inch  Ames  M.  L.  rifle  was  used,  and  steel  shell 
weighing  122  pounds,  containing  2.3  pounds  of  dynamite 
No.  2,  were  fired  with  powder-charges  of  23  pounds.  These 
shell  were  fused  and  filled  with  base-plugs  for  convenience  in 
loading.  Seven  shots  were  successfully  fired  at  a  section  of 
a  wrought-iron  monitor  turret  at  the  distance  of  no  yards. 

Experiments  with  Shell  charged  with  Explosive  Gela- 
tine.— In  1883  an  Ordnance  Board,  U.  S.  Army,  fired  from 
the  3-inch  wrought-iron  field-gun  five  shell,  each  charged  with 
6£  ounces  of  explosive  gelatine  and  fitted  with  Schenkle  per- 
cussion fuses.  All  the  shell  burst  after  leaving  the  gun  and 
before  reaching  the  target.  The  explosive  had  been  on  hand 
for  some  time.  These  experiments  were  continued  during  the 
same  year,  the  same  gun,  but  a  new  lot  of  Nobel's  explosive 
gelatine  and  new  projectiles,  being  used.  The  first  shell  broke 
up  on  leaving  the  gun,  and  the  second  struck  the  target  side- 
ways and  broke  in  pieces.  Five  other  rounds  were  fired,  and 
all  of  them  broke  up  prematurely.  It  was  thought  that  the 
want  of  success  was  due  to  the  heat  generated  by  friction 
between  the  rotating  projectile  and  the  explosive;  therefore 
three  projectiles  were  made  for  trial  with  the  3.2-inch  gun,  in 
which  the  difficulty  was  avoided,  but  with  no  greater  success. 

Further  experiments  were  conducted  with  the  8-inch  con- 
verted M.  L.  rifle.  New  cast-iron  projectiles  were  made, 
having  ogival  heads  which  were  connected  to  the  body  by 
means  of  screw-threads.  To  avoid  friction  between  the  explo- 
sive and  the  walls  of  the  projectile,  the  explosive  was  packed 


THE    USE   OF  HIGH  EXPLOSIVES  IN  SHELL. 

in  a  pasteboard  cylinder  divided  longitudinally  into  four 
compartments  by  two  pieces  of  wood.  The  cylinder  fitted 
the  shell  loosely,  and  was  coated  on  the  exterior  with  plum- 
bago and  tallow.  The  shell  contained  about  five  pounds  of 
explosive  gelatine,  and  the  powder-charge  consisted  of  forty 
pounds  of  Dupont  S.  H.  powder.  Between  the  gunpowder- 
charge  and  shell  was  interposed  a  hollow  rubber  buffer  six 
inches  long  and  one.  inch  thick.  The  first  and  third  shell 
broke  up  on  impact,  the  second  separating  as  it  left  the  gun. 

A  new  shell  was  next  made  and  tested.  In  it  the  explo- 
sive was  made  to  revolve  with  the  projectile  by  means  of  a 
copper  diaphragm  let  into  grooves  cut  into  the  interior  walls 
of  the  shell.  This  shell  proved  successful,  but  a  heavier  and 
stronger  steel  shell  with  a  solid  head  and  heavy  screw  base- 
plug  destroyed  the  gun.  At  first  this  accident  was  attributed 
to  the  fact  that  the  gelatine  was  old  and  uncamphorated,  but 
a  second  round  in  which  new  camphorated  gelatine  was  used 
also  burst  in  the  muzzle  of  the  gun. 

It  is  but  fair  to  observe,  however,  that  during  these  trials 
three  Butler  shell  charged  with  gunpowder  and  fused  with 
fulminate  fuses  broke  in  precisely  the  same  manner  as  did 
those  containing  gelatine.  Subsequent  experiments  with 
explosive  gelatine  as  a  bursting  charge  for  shell  fired  from 
powder-guns  have  proved  equally  unsuccessful. 

Experiments  with  Shell  Charged  with  Hellhoffite.— 
The  principle  employed  in  using  high  explosives  as  a  charge 
for  projectiles  is  applicable  to  explosives  of  the  Sprengel  class 
as  well  as  to  those  already  enumerated.  As  applied  to  this 
special  class  of  explosives,  it  consists  in  placing  the  ingredients 
in  the  shell  in  separate  vessels  of  glass,  porcelain,  or  similar 
material,  which  are  strong  enough  to  resist  the  jolts  and  jars 
incident  to  transportation  and  handling,  but  which  are  broken 
by  the  shock  of  discharge  in  the  gun;  or  it  may  be  done  by 
dividing  the  shell  into  compartments  by  suitable  diaphragms. 
When  the  first  method  is  used  the  vessels  are  encased  in 
rubber,  felt,  or  other  elastic  material  before  being  introduced 
into  the  projectile. 


4IO  LECTURES   ON  EXPLOSIVES. 

In  his  earlier  experiments  with  nellhoffite,  Gruson  placed 
the  nitric  acid  in  the  head  of  the  projectile,  and  the  dinitro- 
benzene  in  the  base.  When  explosion  after  penetration  was 
required  the  ingredients  were  placed  in  reverse  order,  and  a 
delay-action  fuse  in  the  base  retarded  the  operation  of  the 
mixture  until  the  point  of  greatest  penetration  had  been 
attained. 

In  1883  six  15-cm.  shell,  each  containing  i.i  kg.  of  hell- 
hoffite,  were  fired  against  a  parapet.  The  damage  done 
amounted  to  four  times  that  effected  by  a  like  number  of 
shell  charged  with  gunpowder  and  fired  under  similar  condi- 
tions. In  1884  twelve  15-cm.  Gruson  shell,  each  containing 
1.9  kg.  of  hellhoffite,  were  fired  at  Palmanova  with  1.2  kg. 
of  gunpowder,  and  four  rounds  with  1.4  kg.  of  powder. 
Subsequently  three  24-cm.  shell  charged  with  5.53  kg.  of  the 
same  explosive  were  fired  with  4.2  kg.  of  powder.  There 
were  no  premature  explosions,  but,  aside  from  the  inaccuracy 
of  the  projectiles,  the  effect  was  less  than  that  of  similar  shell 
charged  with  guncotton,  although  greater  than  that  of  shell 
charged  with  gunpowder. 

Experiments  with  Shell  Charged  with  Melinite. — Dur- 
ing recent  years  the  attention  of  all  military  powers  has  been 
attracted  by  the  experiments  with  melinite,  conducted  by  the 
French  Government,  but  in  the  majority  of  trials  the  authori- 
ties have  succeeded  in  maintaining  a  strict  secrecy.  The 
results  of  the  Belliqueuse  experiments  are  well  known. 
Although  but  little  effect  was  produced  by  the  melinite- 
charged  shell  on  the  armored  portions  of  the  vessel,  the 
destruction  wrought  by  the  shells  which  penetrated  the 
unarmored  parts  was  so  terrible  as  to  cause  the  naval  experts 
to  recommend  that  all  unfinished  vessels  be  protected  by 
complete  armor  in  order  to  resist  the  fire  of  all  such  projec- 
tiles. 

The  fire  directed  against  the  Belliqueuse  was  from  14- cm. 
and  i6-cm.  guns  of  the  model  of  iSSi,  and  the  shell,  weigh- 
ing 66  and  99  pounds,  were  charged  respectively  with  6.2  and 
8.8  pounds  of  melinite. 


THE    USE   OF  HIGH  EXPLOSIVES   IN  SHELL.  4!  I 

Dumas-Guilin  states  that  shell  containing  33  kg.  of  meli- 
nite have  been  fired  at  Bourges,  and  that  the  effect  produced 
by  melinite  shell  is  fully  equal  to  that  produced  by  the 
Germans  with  guncotton  shell.  Recent  reports  claim  that 
melinite  shell  have  been  repeatedly  and  successfully  fired  from 
high-power  powder-guns,  under  service  conditions,  with  ve- 
locities as  high  as  2000  feet  per  second,  and  it  is  an  estab- 
lished fact  that  charges  of  nearly  70  pounds  have  been  fired 
from  22-cm.  mortars  with  velocities  exceeding  1300  feet  per 
second.  According  to  Professor  Munroe,  from  whose  excel- 
lent course  of  lectures  I  have  so  largely  borrowed  in  the  pre- 
ceding pages,  we  are  more  likely  to  find  the  high  explosive 
for  use  in  shell  among  the  nitro-substitution  compounds 
than  among  the  nitric  esters. 


LECTURE    XXII. 

EXPLOSION   BY   INFLUENCE,    OR   SYMPATHETIC    EXPLOSION. 

IN  considering  the  various  theories  which  have  been  pro- 
posed by  investigators  in  explanation  of  the  phenomena 
attending  the  explosion  of  different  explosive  substances,  the 
subtility  and  plausibility  of  their  reasoning  together  with  the 
originality  and  delicacy  of  their  experiments,  lead  us  to  over- 
look certain  well-known  and  generally  accepted  facts. 

Both  explosion  and  detonation  may  be  considered  as  but 
different  phases  of  the  common  and  daily  occurring  phenome- 
non known  as  combustion,  in  which  the  element  of  time 
varies  between  very  wide  limits. 

We  are  well  aware  of  the  fact  that  the  application  of  heat, 
directly  or  indirectly,  is  the  principal  means  of  producing  an 
explosion,  and  this  is  equally  true  in  the  case  of  combustion 
and  detonation.  It  has  been  pointed  out  that  the  mode  of 
producing  the  heat  also  exercises  a  very  important  influence 
upon  the  nature  or  the  explosive  reaction — so  much  so,  in  fact, 
that  it  is  possible  to  cause  the  same  explosive  to  burn,  explode, 
or  detonate,  according  to  the  circumstances  attending  the 
transformation. 

Explosion  by  Influence,  or  Sympathetic  Explosion. — 
Detonation  has  been  defined  as  the  instantaneous  explosion 
of  the  whole  mass  of  a  body,  and  it  is  a  peculiarity  of  a 
detonating  explosion,  that  when  produced  in  a  body  it  may 
induce  a  similar  explosion  in  another  portion  of  the  same  body, 
either  when  in  contact  with  it,  or  even  when  only  near  it, 
but  not  in  contact.  In  fact,  it  may  induce  such  an  explosion 
when  separated  from  the  second  portion  by  means  of  a  glass 
or  metal  plate,  or  even  a  mass  of  water,  so  that  no  heated  or 
ignited  particles  can  be  projected  from  one  to  the  other. 

412 


EXPLOSION  BY  INFLUENCE.  413 

This  secondary  explosion  has  been  termed  sympathetic  explo- 
sion, or  explosion  by  influence,  and  has  been  deeply  investigated 
by  several  eminent  scientists. 

Abel's  Investigations. — Abel  has  shown  that  not  only 
would  a  detonating  body  cause  the  detonation  of  another 
mass  of  the  same  body,  but  that  it  would  cause  also  the 
detonation  of  other  bodies.  For  instance,  by  detonating 
mercury  fulminate  in  contact  with  guncotton  or  nitroglycerine 
these  bodies  were  also  readily  detonated.  Only  a  small 
quantity  of  fulminate  was  required,  0.32  of  a  gramme 
(5  grains),  when  confined  in  a  sheet-metal  cap  and  placed  in 
direct  contact  with  the  nitroglycerine  or  compressed  gun- 
cotton,  being  sufficient  to  cause  the  detonation  of  the  latter. 

He  found  that  a  mass  of  nitroglycerine  by  its  explosion 
would  cause  the  explosion  of  another  mass  of  nitroglycerine, 
even  though  both  were  immersed  in  water.  His  experiments 
further  showed  that  a  peculiar  kind  of  initial  detonation  or 
explosion  was  required  in  order  to  cause  the  detonation  of 
another  explosive.  For  instance,  while  the  detonation  of 
guncotton  would  cause  the  detonation  of  nitroglycerine  in 
close  proximity  to  it,  the  detonation  of  nitroglycerine  would 
not  cause  the  detonation  of  guncotton. 

This  shows  that  this  property  of  causing  detonation  does 
not  depend  alone  upon  the  force  of  the  detonator,  for  we 
know  that  nitroglycerine  is  more  powerful  than  guncotton. 
Again,  silver  fulminate,  which  explodes  more  violently  and 
sharply  than  mercury  fulminate,  and  nitrogen  iodide,  and 
nitrogen  chloride,  which  are  the  most  violent  explosives  we 
possess,  are  very  much  less  efficient  in  causing  detonation 
than  mercury  fulminate.  In  the  course  of  his  investigations, 
Abel  was  led  to  the  conclusion  "that  a  particular  explosion 
or  detonation  may  possess  a  power  of  determining,  at  the 
instant  of  its  occurrence,  similar  violent  explosions  in  distinct 
masses  of  the  same  material,  or  in  contiguous  explosive  bodies 
of  other  kinds,  which  power  is  independent  of  or  auxiliary 
to  the  distinct  operation  of  mechanical  force  developed  by 
that  explosion;  that  as  a  particular  musical  vibration  will 


414  LECTURES   ON  EXPLOSIVES. 

establish  synchronous  vibrations  in  particular  bodies  while 
it  will  not  affect  others,  and  as  a  chemical  change  may  be 
wrought  in  a  body  by  its  interception  of  only  particular  waves 
of  light,  so  some  kinds  of  explosions  or  powerful  vibratory 
impulses  may  exert  a  disturbing  influence  over  the  chemical 
equilibrium  of  certain  bodies,  resulting  in  their  sudden  dis- 
integration, which  other  explosives  that  develop  equal  or 
greater  mechanical  force  are  powerless  to  exercise. 

Abel's  Theory  of  Synchronous  Vibrations. — Abel  offers 
the  following  as  being  the  most  satisfactory  explanation  of  the 
remarkable  differences  pointed  out: 

"  The  vibrations  produced  by  a  particular  explosion,  if 
synchronous  with  those  which  would  result  from  the  explosion 
of  a  neighboring  substance,  which  is  in  a  state  of  high  chemi- 
cal tension,  will,  by  their  tendency  to  develop  those  vibra- 
tions, either  determine  the  explosion  of  that  substance,  or  at 
any  rate  greatly  aid  the  disturbing  effect  of  mechanical  force 
suddenly  applied  ;  while  in  the  case  of  another  explosion  which 
produces  vibrations  of  a  different  character,  the  mechanical 
force  applied  by  its  agency  has  to  operate  with  little  or  no 
aid;  greater  force  or  more  powerful  detonation  must,  there- 
fore, be  applied  in  the  latter  instance,  if  the  explosion  of  the 
same  substance  is  to  be  accomplished." 

That  vibrations  will  induce  the  decomposition  of  chemical 
compounds  whose  atoms  are  in  a  state  of  unstable  equilib- 
rium is  a  fact  too  well  established  in  science  to  be  dwelt 
upon. 

Investigations  of  Champion  and  Pellet. — This  theory 
was  examined  experimentally  by  MM.  Champion  and  Pellet. 
They  took  a  tube  seven  metres  long,  made  in  two  lengths 
and  joined  by  a  paper  band.  Small  quantities  of  nitrogen 
iodide  were  placed  in  each  end,  and  when  one  was  exploded  it 
immediately  caused  the  explosion  of  the  iodide  at  the  other 
end:  but  if  the  paper  band  connecting  the  two  lengths  was 
removed,  the  second  explosion  did  not  occur.  By  a  suitable 
apparatus  it  was  shown  that  the  effect  produced  was  not  due 
to  the  action  of  a  puff  of  air,  but  to  vibrations  of  the  air  such 


EXPLOSION  BY  INFLUENCE.  415 

as  are  caused  by  a  sounding  body.  When  nitrogen  iodide 
was  attached  to  the  strings  of  a  double  bass  and  the  string 
was  bowed,  the  iodide  exploded  when  placed  on  the  string 
giving  the  highest  rate,  but  not  when  on  the  two  lower  strings. 
The  lowest  number  of  vibrations  which  would  cause  explo- 
sion was  found  to  be  thirty  per  second. 

Similar  results  were  obtained  with  other  musical  instru- 
ments. A  further  set  of  experiments  was  made  to  determine 
the  difference  between  the  vibrating  motion  excited  by 
various  detonants,  and  thus  to  account  for  the  differences 
in  their  ability  to  provoke,  by  means  of  the  intervening  air, 
the  explosion  of  other  detonants  placed  at  a  distance.  A 
series  of  sensitive  flames  was  arranged,  corresponding  to  the 
complete  scale  of  G  major,  and  0.03  gramme  of  mercury  fulmi- 
nate excited  the  a,  c,  e,f,  and  g.  A  like  quantity  of  nitrogen 
iodide  when  exploded  under  similar  conditions  produced  no 
effect.  This  showed  that  the  vibrations  excited  by  the  two 
explosives  were  very  different,  and  also  that  the  vibrations 
excited  by  the  mercury  fulminate  affect  flames  belonging  to 
some  notes  of  the  scale  to  the  exclusion  of  others. 

On  exploding  these  substances  nearer  the  flames  than  in 
the  former  experiment,  while  the  nitrogen  iodide  excited  only 
flames  corresponding  to  the  higher  notes  of  the  scale,  the 
mercury  fulminate  affected  them  all.  In  these  experiments 
it  was  observed  that  acute  sounds  predominate  in  explosions. 

The  same  investigators  took  conjugate  parabolic  mirrors, 
covered  their  surfaces  with  lampblack  so  as  to  prevent  the 
reflection  and  concentration  of  heat-rays  from  them,  placed 
them  2.5  metres  apart,  and  distributed  small  masses  of  nitro- 
glycerine and  of  nitrogen  iodide  at  different  points  along  the 
line  of  foci.  They  then  detonated  a  large  drop  of  nitro- 
glycerine at  one  of  the  foci,  and  observed  that  the  substances 
placed  in  the  corresponding  conjugate  focus  detonated,  but 
that  the  rest  remained  unaffected.  This  same  line  of  investi- 
gation was  continued  by  Abel,  who  claimed  that  his  results 
tended  to  confirm  his  theory. 

Berthelot's   Investigations. — Berthelot    contended   that 


LECTURES   ON  EXPLOSIVES. 

not  only  were  these  experiments  inconclusive,  but,  from  his 
point  of  view,  several  of  them  appeared  directly  opposed  to 
Abel's  theory.  He  noted  in  the  first  place  that  the  charac- 
teristic feature  of  the  given  musical  note,  which  is  capable  of 
determining  each  variety  of  explosion,  had  never  been  estab- 
lished; that  it  was  only  below  a  certain  note  that  the  effects 
ceased  to  be  produced;  while  the  various  explosive  sub- 
stances, almost  without  exception,  proved  particularly  sensi- 
tive to  the  action  of  the  most  acute  notes.  Moreover,  these 
effects  ceased  to  be  produced  at  distances  which  were  incom- 
parably less  than  the  resonance  of  the  chords  in  unison,  and 
this  fact,  he  claimed,  proved  that  the  detonations  were  func- 
tions of  the  intensity  of  the  mechanical  action,  rather  than  of 
the  character  of  the  determining  vibration.  Similarly,  the 
detonation  ceased  to  be  produced  when  the  weight  of  the 
detonating  substance  was  very  slight,  and  when  in  conse- 
quence the  mechanical  energy  of  the  shock  was  greatly  weak- 
ened. Yet  if  the  theory  of  "  synchronous  vibrations  "  were 
true,  the  specific  vibratory  note  which  determines  the  explo- 
sion should  always  remain  the  same.  For  instance,  cartridges 
filled  with  dynamite  No.  I  cannot  be  detonated  by  a  cap 
containing  less  than  0.2  gramme  of  fulminate,  and  the  detona- 
tion is  assured  only  when  the  detonator  contains  one  full 
gramme  of  the  fulminate. 

This,  the  investigator  claims,  establishes  the  fact  of  the 
existence  of  a  direct  relation  between  the  character  of  the 
detonation  and  the  intensity  of  the  shock  produced  by  one 
and  the  same  detonating  substance. 

If  it  be  true  that  guncotton  will  cause  the  detonation  of 
nitroglycerine  in  consequence  of  the  synchronism  of  the 
vibration  communicated,  then  the  effect  of  these  substances 
upon  each  other  should  be  reciprocal,  and  the  failure  of  nitro- 
glycerine to  detonate  guncotton,  therefore,  is  due  to  the 
difference  in  the  structure  of  the  two  substances,  which  plays 
a  very  important  part  in  the  transformation  of  the  mechanical 
energy  into  work.  This  diversity  of  structure  and  the  modifi- 
cations which  it  causes  in  the  transformation  of  the  phenomena 


EXPLOSION  BY  INFLUENCE.  417 

of  the  shock,  and  the  transformation  of  the  mechanical  energy 
into  thermal  energy,  may  be  cited  to  explain  the  facts 
observed  by  Abel. 

All  the  effects  observed  with  nitrogen  iodide  may  be 
explained  by  the  vibration  of  the  supports  and  by  the  friction 
resulting  therefrom.  The  experiment  with  the  conjugate 
mirrors  may  be  explained  by  the  mechanical  effects  resulting 
from  the  movement  of  the  air  when  concentrated  in  the  focus. 
Moreover,  M.  Lambert  has  shown  experimentally  that  in 
the  explosion  of  dynamite  cartridges  in  cast-iron  tubes  of 
large  diameter,  regarded  from  the  standpoint  of  detonation 
by  influence,  there  does  not  appear  to  be  any  difference 
between  the  ventral  segments  and  the  nodes  characteristic  of 
the  tube.  To  clear  up  this  matter  by  eliminating  the  influence 
of  the  supports,  and  the  diversity  existing  in  the  cohesion 
and  physical  structure  of  the  solid  explosive  substances  used, 
Berthelot  undertook  a  series  of  experiments  on  the  chemical 
stability  of  matter  in  sonorous  vibration,  and  especially  on 
that  of  gaseous  bodies  such  as  ozone  and  hydrogen  arsenide, 
or  liquids  such  as  hydrogen  peroxide  and  persulphuric  acid ; 
all  of  these  bodies  being  selected  from  among  those  which 
decompose  with  the  disengagement  of  heat,  precisely  as 
explosive  substances  do. 

The  experiments  were  made  by  enclosing  the  substances 
in  glass  vessels  which  were  attached  to  one  arm  of  a  tuning- 
fork,  which  vibrated  at  the  rate  of  one  hundred  single  vibra- 
tions per  second,  or  by  enclosing  them  in  a  glass  tube  which, 
by  means  of  a  rubber,  was  made  to  give  7200  single  vibrations 
per  second.  The  substances  were  analyzed,  and  then  sub- 
jected to  the  vibratory  action  for  periods  varying  from  one- 
half  to  one  and  one-half  hours  and  then  analyzed  again.  In 
no  case  had  there  been  any  notable  decomposition,  whence 
the  investigator  concluded  that  endothermous  bodies  were 
stable  under  the  influence  of  sound-waves,  but  were  decom- 
posed under  the  influence  of  ethereal  vibrations. 

Berthelot's  Theory. — From  the  consideration  of  these 
facts,  and  especially  from  experiments  made  in  firing  under 


LECTURES   ON  EXPLOSIVES. 

water,  Berthelot  concluded  that  explosions  by  influence,  like 
detonations  in  contact,  were  due  to  the  transmission  of  a  shock, 
arising  from  the  enormous  and  sudden  pressure  by  the  explo- 
sive, which  is  converted  into  heat  within  the  explosive  material 
itself.  Thus,  in  the  extremely  rapid  reaction  which  obtains, 
the  pressures  produced  may  approach  to  the  limit  which  corre- 
sponds to  the  matter  detonating  in  its  own  volume,  and  the 
commotion  due  to  this  sudden  development  of  almost  theo- 
retical pressures  can  be  propagated  through  the  ground  and 
supports  as  intermediaries,  or  through  the  air  itself,  being 
projected  en  masse,  as  has  been  shown  in  the  explosion  of  cer- 
tain powder  factories  and  guncotton  magazines,  and  in  some 
of  the  experiments  made  with  dynamite  and  compressed 
guncotton. 

The  intensity  of  the  shock  propagated,  either  by  a  column 
of  air  or  a  liquid  or  solid  mass,  varies  with  the  nature  of 
the  explosive  body  and  its  mode  of  inflammation;  it  is  of 
greater  violence  according  as  the  duration  of  the  chemical 
reaction  is  shorter  and  develops  more  gas,  that  is  to  say,  a 
higher  initial  pressure  and  more  heat,  and  consequently  more 
work  for  the  same  weight  of  explosive  material.  This  shock 
is  transmitted  better  by  solids  than  by  liquids,  better  by 
liquids  than  by  gases;  with  gases  it  is  better,  as  they  are  more 
compressed.  Through  solids  it  is  better  propagated  according 
to  their  degree  of  hardness.  All  breaks  of  continuity  in  the 
transmitting  material  tend  to  weaken  it,  especially  if  a  softer 
substance  is  interposed.  Thus  it  is  that  the  use  of  a  tube 
made  from  a  goose-quill  as  a  receiver  stops  the  effect  of 
mercury  fulminate,  while  a  tube  or  a  capsule  of  copper  trans- 
mits this  effect  in  all  its  intensity. 

Explosion  by  influence  is  the  better  propagated  in  a 
series  of  cartridges,  according  as  the  envelope  of  the  first 
detonating  cartridge  is  the  more  resisting,  as  it  thus  enables 
the  gases  to  obtain  a  greater  pressure  before  the  covering  is 
destroyed. 

The  existence  of  an  empty  space,  that  is  to  say,  one  filled 
only  with  air  between  the  fulminate  and  the  dynamite,  dimin- 


EXPLOSION  BY  INFLUENCE.  419 

ishes  the  violence  of  the  shock  transmitted,  and  in  conse- 
quence that  of  the  explosion,  and  in  general  the  effects  of 
violent  powders  are  lessened  when  there  is  no  contact. 

To  form  a  full  conception  of  the  transmission  by  the 
medium  of  sudden  pressures  which  produce  shock,  it  is  desir- 
able to  recall  the  general  principle  in  virtue  of  which  pressures 
are  transmitted  in  a  homogeneous  mass  equally  in  all  direc- 
tions, and  are  the  same  on  any  small  element  of  the  surface 
whatever  its  position.  Detonations  produced  under  water 
with  guncotton  show  that  this  principle  is  equally  applicable 
to  the  sudden  pressures  which  produce  explosive  phenomena. 
But  it  ceases  to  be  true  when  one  passes  from  one  medium  to 
another. 

If  the  inert  chemical  matter  which  transmits  the  explosive 
movement  is  fixed  in  a  given  situation  like  the  surface  of  the 
ground,  or,  better  still,  held  by  the  pressure  of  a  mass  of  deep 
water,  in  the  midst  of  which  the  first  detonation  is  produced, 
the  propagation  of  the  movement  in  this  medium  will  hardly 
be  able  to  take  place,  except  under  the  form  of  a  wave  of 
purely  physical  order,  and  consequently  of  an  essentially 
different  character  from  the  original  wave  which  is  developed 
in  the  explosive  body  itself,  and  which  is  of  a  chemical  and 
physical  order.  Whilst  the  first  wave,  which  is  of  a  chemical 
order,  is  propagated  with  a  constant  intensity,  the  new  wave, 
which  is  of  a  physical  order,  transmits  the  concussion  away 
from  the  explosive  centre  all  around  it  with  an  intensity  which 
decreases  inversely  as  the  square  of  the  distance.  In  the 
neighborhood  of  the  centre  of  the  explosion  the  displace- 
ments of  the  molecules  may  overcome  the  cohesion  of  the 
mass  and  disperse  it,  or  crush  it  by  enlarging  the  explosion- 
chamber  if  the  operation  is  conducted  in  a  cavity.  But  at 
a  very  short  distance  (the  magnitude  of  which  depends  on  the 
elasticity  of  the  surrounding  medium)  these  movements,  con- 
fused at  the  beginning,  arrange  themselves  in  such  order  as  to 
produce  a  wave,  properly  so  called. 

Characterized  by  compressions  and  sudden  deformations 
of  the  material,  the  amplitude  of  these  oscillations  depends 


42O  LECTURES   ON  EXPLOSIVES. 

upon  the  magnitude  of  the  initial  impulse.  They  move  with 
a  very  great  rapidity,  and  preserve  their  irregularity  up  to  the 
point  where  the  continuity  of  the  medium  is  interrupted; 
then  these  compressions  and  sudden  deformations  change 
their  nature,  and  are  transformed  into  a  movement  of  impulse, 
that  is  to  say,  they  reproduce  the  shock.  If  then  they  act  on 
a  new  cartridge,  they  may  determine  its  explosion;  the  shock 
will  be  otherwise  weakened  by  the  distance,  and  in  conse- 
quence the  character  of  the  explosion  may  be  modified.  The 
effects  diminish  in  this  manner  up  to  a  certain  point,  from 
which  the  explosion  ceases  to  produce  itself.  When  this 
occurs  with  a  second  cartridge,  the  same  series  of  effects  will 
be  continued  from  the  second  to  the  third  cartridge;  but  this 
depends  on  the  character  of  the  explosion  which  the  second 
cartridge  undergoes.  And  thus  it  goes  on. 

Such  is  the  theory  that  Berthelot  offers  to  explain  explo- 
sions by  influence,  and  the  phenomena  which  accompany 
them.  It  depends  definitely  on  the  production  of  two 
orders  of  waves,  one  series  representing  the  explosive  waves, 
properly  so  called,  developed  in  the  midst  of  the  matter 
which  detonates,  and  consisting  of  a  continually  reproduced 
transformation  of  chemical  actions  into  thermal  and  mechanical 
actions,  which  transmit  the  shock  to  the  support  and  to  the 
contiguous  bodies;  the  other  being  a  purely  mechanical  and 
physical  series,  which  transmits  the  sudden  pressure  equally 
about  the  centre  of  the  concussion  to  the  adjoining  bodies 
and,  by  a  singular  circumstance,  to  a  new  mass  of  explosive 
material.  As  to  the  action  within  the  original  mass,  he  holds 
that  the  kinetic  energy  of  the  shock  of  the  explosion  (by  the 
detonator)  is  transformed  into  heat  at  the  point  struck;  the 
temperature  of  this  point  is  thus  raised  to  the  temperature  of 
explosion,  a  new  shock  is  produced  which  raises  the  tempera- 
ture of  the  neighboring  portions  to  the  same  degree;  they 
then  explode,  and  the  action  is  propagated  with  an  ever-in- 
creasing velocity. 

Threlfall's  Investigations. — Neither  Abel's  theory  of 
synchronous  vibrations  nor  Berthelot's  wave  theory  satisfied 


EXPLOSION  BY  INFLUENCE.  421 

Thre-lfall,  and  he  therefore  made  an  experimental  and  critical 
study  of  the  manner  in  which  the  explosive  reaction  is  com- 
municated from  one  explosive  mass  to  another  explosive  mass 
through  a  non-explosive  medium.  Much  might  be  learned 
from  a  measurement  of  the  velocity  of  transmission  of  a  shock 
to  points  at  small  distances  from  the  centre  of  explosion. 
This  would  be  merely  a  question  of  experiment,  and  Lord 
Rayleigh  suggested  the  use  of  a  sensitive  flame  and  revolving 
mirror,  which  would,  at  all  events,  give  some  idea  of  the  sort 
of  disturbance  experienced;  but  Threlfall  deemed  it  best  to 
begin  by  examining  cases  where  the  results  of  explosion  could 
be  seen  and  watched.  For  this  purpose  he  constructed  a 
tank  measuring  a  yard  each  way,  and  provided  with  windows 
in  the  sides.  The  tank  was  filled  with  water,  and  water-tight 
glass  bulbs  of  one-half  inch  diameter,  filled  with  mercury 
fulminate,  were  sunk  to  the  depth  of  eighteen  inches  in  the 
water,  fired  by  electricity,  and  the  course  of  the  debris  from 
the  explosion  noted.  As  the  torpedo  was  suspended  ver- 
tically, this  debris  had  the  appearance  of  being  shot  down  to 
the  bottom  of  the  tank,  not  in  a  jet  as  might  have  been 
expected,  but  with  exactly  the  rolling  motion  that  smoke  has 
in  coming  out  of  a  chimney — as  if,  in  fact,  there  were  vortex 
motion  of  some  sort. 

The  constancy  of  the  downward  action  of  the  explosion 
suggested  that  it  was  due  to  the  want  of  symmetry  introduced 
by  the  neck  and  wires  of  the  torpedo.  Hence  experiments 
were  made  in  which  the  torpedoes  were  placed  horizontally, 
and  then  the  debris  seemed  to  move  with  its  peculiar  rolling 
motion  horizontally  away  from  the  neck.  In  fact,  the  ap- 
pearance presented  to  the  unaided  eye  was  that  of  a  more  or 
less  definite  column  of  rolling  white  smoke  shot  out  with  great 
velocity,  and  coming  to  rest  very  rapidly  when  about  five 
inches  from  the  centre,  as  if  acted  upon  with  an  irresistible 
force.  Experiments  were  also  made  by  exploding  a  charge 
in  the  centre  of  a  Florence  oil-flask,  filled  with  red  dye  and 
immersed  in  the  water.  The  dye  was  shot  out  with  the 
debris,  and  the  flash  appeared  to  be  suddenly  stopped  some 


422  LECTURES   ON  EXPLOSIVES. 

two  or  three  inches  outside  where  the  flask  would  have  been 
if  it  had  not  disappeared.  There  were,  however,  so  many 
sources  of  misinterpretation  to  be  feared  in  this  method  of 
observation  that  it  was  not  continued,  but  the  experimenter 
contented  himself  with  noting  the  peculiar  rolling  motion  of 
the  dye  as  it  was  shot  out. 

Experiments  were  now  made  to  determine  if  the  direc- 
tions of  projection  of  the  debris  coincided  with  the  directions 
of  propagation  of  the  stream  of  explosive  energy.  For  this 
purpose  a  pendulum  gauge  was  devised  which  was  fitted  to 
the  tank,  and  by  firing  some  dozen  torpedoes,  arranged  as 
symmetrically  as  possible,  he  found  that  the  indications  of  the 
gauges  were  nearly  proportioned.  Explosions  were  then 
produced  in  torpedoes  purposely  made  unsymmetrical,  either 
by  having  the  glass  too  thick  on  one  side,  or  by  turning  up 
the  ends  of  the  covered  conducting  wires,  so  that  they  entered 
the  bulb  horizontally  and  facing  one  of  the  gauges. 

The  effects  now  became  more  puzzling,  but  on  the  whole 
there  was  no  question  but  that  the  gauge  towards  which  the 
bulb  was  turned  suffered  most.  In  fact,  the  direction  taken 
by  the  streams  of  explosive  energy  appeared  to  coincide  with 
the  directions  of  projection  of  debris,  and  with  the  direction 
foretold  from  the  initial  conditions.  The  experiments  were 
repeated  at  various  distances,  and  in  various  manners  with 
more  or  less  compressed  charges,  and  with  variations  in  the 
position  of  the  firing-point.  The  pendulum  readings  were  on 
the  whole  proportional  to  the  direction  of  explosion  as  fore- 
told from  the  initial  conditions. 

Of  course,  in  some  few  cases,  there  were  unexpected 
actions  on  the  gauges,  but  this  was  hardly  avoidable,  since 
the  previous  experiments  had  shown  how  small  a  change  in 
initial  conditions  could  lead  to  great  variations  in  the  result. 
The  position  of  the  firing-point  was  the  least  satisfactory 
part  of  the  experiments;  most  of  the  failures  could  be  traced 
to  imperfect  centring  of  the  firing-point;  about  ten  per  cent 
of  the  experiments  failed  to  travel  on  the  paths  laid  out  for 
them.  These  experiments  leave  little  doubt  that  the  dirac- 


EXPLOSION  BY  INFLUENCE.  423 

tion  in  which  the  maximum  explosive  effect  is  transmitted 
will  in  a  great  measure  depend  on  the  initial  arrangement  of 
surrounding  obstacles;  at  all  events,  when  the  explosion  is 
caused  by  fulminate  of  mercury  and  small  charges  are  used. 
In  fact,  the  shock  of  an  explosion  must  be  transmitted  in  one 
or  more  of  three  different  ways: 

Threlfall's  Theory. — As  the  result  of  his  investigations, 
Threlfall  concluded  that  the  shock  of  an  explosion  must  be 
transmitted  in  one  of  three  ways,  or  by  a  combination  of  two 
or  of  all  three  ways,  as  follows: 

1.  By  actual  bodily  motion  of  the  products  of  explosion 
through  the  surrounding  medium,  either  alone  or  becoming 
more  and  more  mixed  up  with  the  medium  itself,  which  is 
thereby  set  in  motion. 

2.  By  an  undulating  motion  set  up  in  the  medium. 

3.  By  vortex-ring  motion. 

In  the  explosion  of  gunpowder  and  other  slow  explosives 
the  energy  is  transmitted  chiefly  by  I  and  2.  The  distance 
to  which  a  considerable  quantity  of  the  energy  may  be  con- 
veyed by  means  of  waves  of  comparatively  great  amplitude 
is  in  some  cases  remarkably  great.  This  is  evidenced  by  the 
effects  produced  by  the  explosion  of  powder-magazines. 

In  the  case  of  the  fulminates  of  mercury  and  silver,  gun- 
cotton  and  nitroglycerine,  that  is,  explosives  of  the  class 
examined  under  water,  the  effect  falls  off  very  rapidly  with 
the  distance,  and  in  water,  at  all  events,  is  of  a  directed  char- 
acter. This  would  point  to  the  third  mode  of  transmission 
being  in  these  cases  of  some  importance,  and  if  we  consider 
the  way  in  which  the  products  of  explosion  escape,  we  shall 
find  that  the  conditions  for  the  production  of  vortex  motion 
do  exist.  Let  there  be  a  sphere  of  mercury  fulminate  fired 
from  its  geometrical  centre,  then,  by  Vieille's  experiments  on 
the  time  of  explosion,  it  seems  likely  that  the  outer  portions 
of  the  fulminate  will  be  decomposed  before  they  are  removed 
to  any  appreciable  distance  from  their  original  positions. 

We  shall  therefore  have  a  sudden  expansion  in  all  direc- 
tions, caused  by  the  increase  in  volume  of  the  explosive 


424  LECTURES   ON  EXPLOSIVES. 

substance  during  the  explosion.  There  seems  no  reason  why, 
under  perfectly  symmetrical  conditions,  the  expansion  should 
not  go  on  as  it  began  until  the  cooling  of  the  sphere  of  hot 
gases  becomes  so  marked  as  to  prevent  further  expansion. 
If  the  conditions,  however,  are  not  such  as  to  allow  of  sym- 
metrical expansion,  which  occurs  in  practice,  then  we  shall 
have  the  bounding  surface  of  the  explosion-gases  more  curved 
in  some  places  than  in  others,  that  is,  the  strain  will  be  greater 
at  some  parts  than  at  others,  and  in  fact  may  become  so 
great  at  points  of  greatest  curvature  as  to  lead  to  a  state  of 
"  breakdown."  In  other  words,  the  compressed  gases  in  this 
case  escape,  not  by  gradual  expansion,  but  by  jets,  from 
points  whose  positions  are  fixed  by  the  conditions  of  explo- 
sion. In  these  jets  we  should  have  the  necessary  and  suffi- 
cient conditions  for  the  establishment  of  vortex  motion.  If 
vortex  motion  were  set  up,  then  it  seems  likely  that  much 
greater  effects  might  be  transmitted  in  some  directions  than 
in  others,  though  at  considerable  distances  the  effects  would 
tend  to  become  uniform  in  all  directions.  Threlfall  believes 
that  this  view  of  the  actions  of  explosions  will  enable  us  to 
explain  several  difficulties  occurring  in  the  interpretation  of 
Abel's  experiments.  Among  these  are:  the  want  of  corre- 
spondence between  the  explosive  actions,  as  measured  by 
the  effect  produced  on  copper  plates,  and  the  effects  pro- 
duced in  causing  explosions;  the  apparent  capriciousness  of 
explosions  of  the  more  violent  kinds;  and,  finally,  the  pro- 
duction of  explosions  by  influence. 

The  investigations  of  these  eminent  scientists,  and  the 
theories  advanced  by  them  in  explanation  of  the  observed 
phenomena,  have  been  ably  reviewed  by  Professor  C.  E. 
Munroe,  Chemist  to  the  U.  S.  Naval  Torpedo  Corps.  While 
recognizing  the  plausibility  of  the  theory  advanced  by 
Berthelot,  and  admitting  that  his  views  are  in  a  measure 
supported  by  experiments.  Professor  Munroe  is  unwilling  to 
accept  this  theory  in  its  entirety.  In  fact,  he  rather  inclines 
to  Abel's  theory  of  "synchronous  vibrations."  Touching 
the  investigations  of  MM.  Champion  and  Pellet,  the  only 


EXPLOSION  BY  INFLUENCE.  42$ 

points  noted  refer  to  the  explosive  substance  used  in  their 
experiments — nitrogen  iodide — and  the  peculiar  conditions 
under  which  the  experiment  with  mirrors  was  performed.  In 
the  first  case,  the  only  cause  for  surprise  or  wonder  is  that  the 
investigators  were  able  to  find  a  string  that  would  vibrate 
sufficiently  slowly  not  to  fire  the  iodide;  while  in  their  efforts 
to  establish  the  theory  of  synchronous  vibrations  by  the  mirror 
experiments,  they  proceeded  to  coat  the  surfaces  of  the 
mirror  with. a  material  (lampblack)  which  would  absorb  the 
vibrations  which,  upon  this  theory,  would  be  most  active  in 
producing  the  desired  effect. 

In  conclusion,  he  claims  that  if  the  synchronous  vibrations 
can  be  disproved  at  all  by  experiment,  then  Abel  himself  has 
contributed  the  strongest  evidence  against  it.  In  the  light  of 
what  has  been  published  on  the  subject,  there  is  sufficient 
reason  for  hesitation  in  accepting  Abel's  theory.  On  the 
other  hand,  if  the  vortex  motion  be  accepted,  several  other- 
wise apparently  inexplicable  phenomena  are  readily  accounted 
for.  At  present,  therefore,  it  would  seem  that  the  capricious- 
ness  of  explosions,  such  as  was  exemplified  in  the  Bremer- 
haven  disaster,  cannot  be  explained  upon  any  theory  of  uni- 
form wave  motion,  but,  on  the  other  hand,  are  readily  explic- 
able upon  the  hypothesis  of  the  coexistence  of  two  states  of 
propagation,  that  of  wave  motion  and  that  of  vortex  motion. 


INDEX. 


PAGE 

Acetone  59 

Acid,  cyanic 355 

cyanuric 355 

Emmens 196 

fulminic 355 

nitric 40 

picric 1 72 

sulphuric 46 

Acrolein •. 55 

Alcohols 53 

Ammonites • 193 

Ammonium  nitrate 32 

picrate... 177 

Apparatus,  heat  test 252 

igniting 378 

sulphur  and  saltpetre  grinding 75 

Asphaline 159 

Balance,  Du  Pont  gravimetric 138 

Ballistite , 323,  339 

Barium  nitrate 32 

Beams,  iron  and  steel,  destruction  of 390 

wooden,  destruction  of 300 

Bellite 185 

Benzene 50,   168 

Blasting-powders,  guncotton 295 

Bridges,  demolition  of. 391 

Bromamide 367 

Caliche 31 

Calorie 15 

Camphor 6r 

Carbodynamite , 305 

Carbohydrates 52 

Carbonite 320 

427 


423  INDEX. 


PAGE 


Cartridge,  dynamite,  how  to  fire 375 

how  to  make 373 

Cellulose 52,   203 

Charcoal 42,  7 1 

Charles,  law  of iC 

Chloramide 364 

Chlorates 154 

qualitative  tests  for 39 

Collodion-cotton , 230 

Combustion   ..    7 

Composition,  Austrian 166 

contact  system . 164 

Davey's 164 

English 165 

frictional  electricity 165 

friction-fuse 164 

fuse 163 

Harvey's , 165 

Hill's 164 

Compounds,  explosive 25,   167 

subdivision  of 26,  167 

nitro-substitution 167 

Connecting- wires. ...    377 

Copper  amine •. ..  > 368 

Cordite 336 

Cresilite 1 8 1 

Cupricamine 368 

Densimeter,  Du  Pont , 129 

Mallet 123 

Densimetry 122 

Derivatives,  nitric    202 

Deterrents 324 

Detonation 7 

bodies  susceptible  of  . 9 

Detonators 360 

Dextrine 52 

Di-nitrobenzene , 184 

Di-nitronaphthalene 190 

Dissociation,  effect  of 16 

Dope « 298 

Dualin 319 

Dynamite 4,  297 

de  Trauzl 321 

gelatine. 311 

No.  i 299 

No.  2 306 

tests  for 312 

with  active  base 304 


INDEX.  429 

PACK 

Dynamite  with  chlorate  mixture  base 307 

combustible  base 305 

explosive  base 306 

nitrate  mixture  base 306 

nitric  derivative  base . .  , 307 

nitro-substitution  product  base 307 

Dynamites 295 

classification  of 298 

Dynamogen ...  161 

Ecrasite 181,  321 

Emmensite 195 

Endotherm 19 

Esters,  nitric 202,  207 

Ether,  acetic 58 

ethylic 58 

, 57 

nitric 202,  263 

Ethyl-alcohol 54 

Exotherm 19 

Explosion 2,  7 

by  influence,  or  sympathetic 412 

investigations  of  Abel 413 

Berthelot 415 

Champion  and  Pellet 414 

Threlfall 420 

theory  of  Abel 414 

Berthelot 417 

Threlfall 423 

first  and  second  order 10 

how  influenced 4 

methods  of  originating 3 

temperature  of 14 

Explosive,  Favier 193 

military,  conditions  to  be  fulfilled  by 388 

Parone's 1 63 

Explosives,  chemical  composition  of 2,  26 

classification  and  constitution  of 21 

general  list  of 22 

high,  Champion's  experiments  with 395 

precautions  to  be  observed  in  handling. 371 

relative  force  of 394 

storage  of 382 

transportation  of 386 

potential  energy  of 17 

safety 201 

Sprengel 346 

practical  value  of 353 

Fluoram ide 368 


430  INDEX. 

PAGE 

Force,  explosive 1 1 

Forcite 312 

Fulminate,  copper 364 

double 364 

mercury , 355 

manufactuce  of 357 

properties  of 358 

platinum 364 

silver 362 

zinc 364 

Fuse,  Bickford 374 

single-  and  double-tape. 374 

sulphuric  acid 164 

time 374 

Fuses,  electrical 375 

Gas,  volume  of 12 

Gelatine,  explosive 308 

military  explosive  310 

tests  for 313 

Gelbite 199 

Gelignite 321 

Glonoine 265 

Glucose 52 

Glyceride,  nitric 267 

Glycerine 55 

Glyceryl  trinitrate 267 

Gravimeter , 140 

Grough ,     29 

Gums 52 

Guncotton 65,  207 

Abel's  improvements  and  patents 212 

adoption  in  United  States 213 

chemistry  of 214 

decomposition  of 220 

explosive  effect  of 226 

manufacture  at  U.  S.  Naval  Torpedo  Station 234 

note  on  drying 248 

percentage  of  nitrogen  contained '. 216 

properties  of 217 

soluble 230 

storage  of 247 

tests  for 249 

alkaline  substances 261 

ash  of 251 

free  acid 251 

moisture 250 

nitrogen 256 

solubility 259 


INDEX,  431 

PAGE 

Guncotton  tests  for  stability 25 1 

temperature  of  ignition    261 

unconverted  cotton 261 

Von  Lenk's  process  of  manufacture 211 

yield  of 215 

Gunpowder 65 

absolute  density  of 107 

analysis  of 108 

chemical  theory  of  combustion  of 143 

composition  of 66 

modifications  in 95 

gravimetric  density  of • 136 

manufacture  of 76 

modifications  in 93 

Augusta  Mills  process 94 

Nordenfelt  and  Meurling  process     95 

Wiener  process 95 

preservation  of 119 

properties  of 106 

special 84 

amide 100 

brown  prismatic  or  cocoa 96 

cubical , 93 

Du  Pont  brown 98 

hexagonal 86 

Nobel's 103 

Pellet 90 

perforated  prismatic 87 

quick 102 

specific  gravity  of 107 

storage  of 119 

tests  for 108 

granulation  and  hardness 118 

hygroscopicity 115 

incorporation 116 

transportation  of ...    1 19 

•"  Hang-fire  " 372 

Heat,  specific , 15 

Hellhoffite 349 

Hydrocarbons 49 

Hygroscope. 116 

Indurite 343 

Inosite 52 

lodoamide   366 

Jelly,  mineral 62,  337 

Kieselguhr 63,  299 

Lactose 52 

Laevulose    52 


43 2  INDEX. 

PAGE 

Lead  nitrate , 32 

Leading-wires 377 

Lignin 52 

Lyddite 182 

Machine,  magneto,  No.  3 378 

Maltose 52 

Mannitose 52 

Material,  artillery,  destruction  of 392 

Melinite 181 

Melitose 52 

Mercury  amine 368 

fulminate 355 

Mill,  charcoal-grinding ....    73 

Mixtures,  explosive 24 

chlorate  class 1 54 

nitrate  class 64 

subdivision  of 26 

Mono-nitrobenzene 182 

Mono-nitronaphthalene 189 

Naphthalene 51 

Nitramidine 208 

Nitramites 193 

Nitrates,  qualitative  tests  for 33 

Nitre 29 

quantitative  tests  for 36 

Nitric-derivatives 167 

Nitrobenzene 168,  182 

Nitro-deri vatives ...    167 

Nitrogen  chloride 5»  3°4 

fluoride - •  •  •  • 3^8 

iodide 368 

sulphide 368 

Nitroglycerine 4.  263 

acid  mixture  used  in  manufacture ^ 270 

analysis  of  preparations 315 

chemistry  of 266 

decomposition  of 287 

discovery  and  early  history  of 263 

explosive  effect  of 293 

how  to  fire 287 

how  to  thaw 284 

manufacture  of 271 

at  Vonges. 279 

properties  of 282 

reduction  of  freezing-point 285 

Sobrero's  investigations  of 269 

solubility  of 283 

tests  for. .    291 


INDEX,  433 


Nitroglycerine  use  in  blasting 289 

yield  from  various  processes 281 

Nitro-hydrocellulose 230 

Nitrostarch 231 

Nitrotoluene 189 

Oil,  detonating • 265 

mirbane 184 

Oxonite - • 35° 

Panclastite 35 1 

Percussion-caps • 360 

Petrofracteur 163 

Picrate,  ammonium 177 

potassium 1 76 

Point,  exploding , 3 

Potassium  chlorate - ....     38 

nitrate 29 

picrate 1 76 

Potentite. 297 

Poudre  B 323,  332 

Poudre  BN 333 

Powder,  Abel's 178 

Abel's  guncotton 297 

^Etna 322 

American  safety 320 

Atlas 319,  322 

Augendre's 159 

Borlinetto's 175 

Brugere 178 

Carboazotine 105 

Castellanos 307 

Cotton  No.  i 296 

Courteille's , 104 

Designolle's * 176 

E.  C 344 

Fontaine's 176 

giant 319,  322 

guncotton 295 

Hahn's 162 

Hecla 322 

Hercules 320,  322 

Horsley's 162,  321 

Judson 320,  322 

Leonard 342 

Maxim's 340 

Melland's  Paper ) 1 59 

Nobel's  Safety. 298 

Normal 335 

Pertuiset's 163 


434  INDEX. 

PAGE 

Powder,  Schultze 344 

S.K 344 

smokeless,  manufacture  of 324 

properties  of 327 

tests  for 329 

S-  R 344 

tonite   296 

triumph  safety 104 

Troisdorf 334 

U.  S.  N.  smokeless 330 

Volney's igi 

Vulcan 320 

W.-A  335 

Wetteren 342 

Powders,  blasting , 104,  295 

smokless 323 

Primer,  how  to  prepare 373 

Py  rolithe 105 

Rack-a-rock 347 

Railway-tracks,  destruction  of 392 

Randanite 63 

Reactions,  explosive i 

origin  of 2 

products  of ii 

propagation  of 3 

Rendrock 320 

Rifleite 343 

Roburite 199 

Romite 352 

Saccharose 52 

Saltpetre 29 

Chili 31 

refining - 66 

Saxifragine 103 

Securite :w 188 

Shell,  experiments  with,  charged  with  dynamite 406 

explosive  gelatine 408 

guncotton 401 

hellhoffite 409 

m61inite 410 

nitroglycerine 405 

precautions  in  loading 381 

Silver  amine 368 

fulminate 362 

hydrazoate 3?o 

Sodium  nitrate 31 

Sprengal,  Nobel's 265 

Starch 52 


INDEX.  435 

PAGE 

Stereochemistry 207 

Stonite 321 

Strontium  nitrate    32 

Substances,  explosive 26 

Sugar,  grape 52 

Sulphur .^ 45,  69 

Tctra-nitronaphthalene 190 

Thermochemistry,  principles  of  . . .  ., .  , 18 

Toluene 51 

Tonite   % 296 

Torpedoes,  precautions  in  loading 381 

Transformations,  chemical 19 

Trees,  felling 389 

Tri-nitrobenzene 185 

Tri-nitrocresol   , 180 

Tri-nitronaphthalene 190 

Tri-nitrophenol „  172 

Vaseline 62 

Velocity,  molecular 3 

Vigorite 307 

Waste,  "  weaver's  "  or  "cop" 234 

Waterways,  removal  of  obstructions  in 393 

Wax,  paraffin 62 

Wires 377 

Work,  maximum 20 

molecular 18 


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